Raises of Internal_FLTK_Error now come with error messages

26 files changed, 215 insertions, 89 deletions

diff --git a/body/c_fl_draw.cpp b/body/c_fl_draw.cpp
index 488a73f..ddf17b0 100644
--- a/body/c_fl_draw.cpp
+++ b/body/c_fl_draw.cpp
@@ -260,8 +260,8 @@ void fl_draw_draw_box(int bk, int x, int y, int w, int h, unsigned int c) {
     fl_draw_box((Fl_Boxtype)bk, x, y, w, h, (Fl_Color)c);
 }
 
-void fl_draw_draw_symbol(const char *label, int x, int y, int w, int h, unsigned int c) {
-    fl_draw_symbol(label, x, y, w, h, (Fl_Color)c);
+int fl_draw_draw_symbol(const char *label, int x, int y, int w, int h, unsigned int c) {
+    return fl_draw_symbol(label, x, y, w, h, (Fl_Color)c);
 }
 
 void fl_draw_measure(const char * str, int &w, int &h, int draw_symbols) {
diff --git a/body/c_fl_draw.h b/body/c_fl_draw.h
index d719903..ae3419f 100644
--- a/body/c_fl_draw.h
+++ b/body/c_fl_draw.h
@@ -80,7 +80,7 @@ extern "C" void fl_draw_draw_text3(const char *str, int x, int y, int w, int h,
 extern "C" void fl_draw_draw_text4(int angle, const char *str, int n, int x, int y);
 extern "C" void fl_draw_rtl_draw(const char *str, int n, int x, int y);
 extern "C" void fl_draw_draw_box(int bk, int x, int y, int w, int h, unsigned int c);
-extern "C" void fl_draw_draw_symbol(const char *label, int x, int y, int w, int h, unsigned int c);
+extern "C" int fl_draw_draw_symbol(const char *label, int x, int y, int w, int h, unsigned int c);
 extern "C" void fl_draw_measure(const char * str, int &w, int &h, int draw_symbols);
 extern "C" void fl_draw_scroll(int x, int y, int w, int h, int dx, int dy,
                                void * func, void * data);
diff --git a/body/fltk-asks.adb b/body/fltk-asks.adb
index bd09fac..d6eb8ee 100644
--- a/body/fltk-asks.adb
+++ b/body/fltk-asks.adb
@@ -402,7 +402,9 @@ package body FLTK.Asks is
         pragma Assert (Result in -3 .. 2);
         return Extended_Choice_Result'Val (Result mod 6);
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "fl_choice_n returned unexpected int value of " &
+        Interfaces.C.int'Image (Result);
     end Extended_Choice;
 
 
@@ -420,7 +422,9 @@ package body FLTK.Asks is
         pragma Assert (Result in -3 .. 2);
         return Extended_Choice_Result'Val (Result mod 6);
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "fl_choice_n returned unexpected int value of " &
+        Interfaces.C.int'Image (Result);
     end Extended_Choice;
 
 
@@ -439,7 +443,9 @@ package body FLTK.Asks is
         pragma Assert (Result in -3 .. 2);
         return Extended_Choice_Result'Val (Result mod 6);
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "fl_choice_n returned unexpected int value of " &
+        Interfaces.C.int'Image (Result);
     end Extended_Choice;
 
 
@@ -512,7 +518,9 @@ package body FLTK.Asks is
             return Cancel;
         end if;
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "fl_color_chooser returned unexpected int value of " &
+        Interfaces.C.int'Image (Result);
     end Color_Chooser;
 
 
@@ -540,7 +548,9 @@ package body FLTK.Asks is
             return Cancel;
         end if;
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "fl_color_chooser returned unexpected int value of " &
+        Interfaces.C.int'Image (Result);
     end Color_Chooser;
 
 
diff --git a/body/fltk-devices-surface-paged-postscript.adb b/body/fltk-devices-surface-paged-postscript.adb
index fa9f66d..b58b1da 100644
--- a/body/fltk-devices-surface-paged-postscript.adb
+++ b/body/fltk-devices-surface-paged-postscript.adb
@@ -355,7 +355,9 @@ package body FLTK.Devices.Surface.Paged.Postscript is
     begin
         pragma Assert (Code = 0);
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Fl_PostScript_File_Device::start_job returned unexpected int value of " &
+        Interfaces.C.int'Image (Code);
     end Start_Job;
 
 
@@ -377,7 +379,9 @@ package body FLTK.Devices.Surface.Paged.Postscript is
         when others => pragma Assert (Code = 0);
         end case;
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Fl_PostScript_File_Device::start_job returned unexpected int value of " &
+        Interfaces.C.int'Image (Code);
     end Start_Job;
 
 
diff --git a/body/fltk-devices-surface-paged.adb b/body/fltk-devices-surface-paged.adb
index 829974a..e13338f 100644
--- a/body/fltk-devices-surface-paged.adb
+++ b/body/fltk-devices-surface-paged.adb
@@ -211,7 +211,7 @@ package body FLTK.Devices.Surface.Paged is
             return Media;
         end if;
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Constraint_Error;
     end To_Page_Format;
 
 
@@ -243,7 +243,7 @@ package body FLTK.Devices.Surface.Paged is
             return Orientation;
         end if;
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Constraint_Error;
     end To_Page_Layout;
 
 
@@ -267,6 +267,10 @@ package body FLTK.Devices.Surface.Paged is
                 Data (Index).My_Height := Natural (C_Height);
             end loop;
         end return;
+    exception
+    when Constraint_Error => raise Internal_FLTK_Error with
+        "Fl_Paged_Device::NO_PAGE_FORMATS has inconsistent value of " &
+        Interfaces.C.int'Image (fl_no_page_formats);
     end Get_Page_Formats;
 
 
diff --git a/body/fltk-draw.adb b/body/fltk-draw.adb
index 8e98a7f..a98edae 100644
--- a/body/fltk-draw.adb
+++ b/body/fltk-draw.adb
@@ -685,7 +685,9 @@ package body FLTK.Draw is
             return False;
         end if;
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "fl_can_do_alpha_blending returned unexpected value of " &
+        Interfaces.C.int'Image (Result);
     end Can_Do_Alpha_Blending;
 
 
@@ -1228,7 +1230,9 @@ package body FLTK.Draw is
         pragma Assert (Buffer = Storage.To_Integer (Result (Result'First)'Address));
         return Result;
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "fl_read_image returned unexpected address value that did not " &
+        "correspond to supplied address value";
     end Read_Image;
 
 
@@ -1254,7 +1258,9 @@ package body FLTK.Draw is
             pragma Assert (Ret_Val = 1);
         end if;
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "fl_add_symbol returned unexpected int value of " &
+        Interfaces.C.int'Image (Ret_Val);
     end Add_Symbol;
 
     procedure Draw_Text
@@ -1423,7 +1429,9 @@ package body FLTK.Draw is
             pragma Assert (Ret_Val = 1);
         end if;
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "fl_draw_symbol returned unexpected int value of " &
+        Interfaces.C.int'Image (Ret_Val);
     end Draw_Symbol;
 
 
diff --git a/body/fltk-environment.adb b/body/fltk-environment.adb
index 22cf676..58c13d6 100644
--- a/body/fltk-environment.adb
+++ b/body/fltk-environment.adb
@@ -392,7 +392,7 @@ package body FLTK.Environment is
             return User;
         end if;
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Constraint_Error;
     end To_Scope;
 
 
diff --git a/body/fltk-event.adb b/body/fltk-event.adb
index 4521fc2..186df71 100644
--- a/body/fltk-event.adb
+++ b/body/fltk-event.adb
@@ -364,7 +364,8 @@ package body FLTK.Event is
         end if;
         return Actual_Grab;
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Widget returned by Fl::grab did not have user_data reference back to Ada";
     end Get_Grab;
 
 
@@ -394,7 +395,8 @@ package body FLTK.Event is
         end if;
         return Actual_Pushed;
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Widget returned by Fl::pushed did not have user_data reference back to Ada";
     end Get_Pushed;
 
 
@@ -418,7 +420,8 @@ package body FLTK.Event is
         end if;
         return Actual_Below;
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Widget returned by Fl::belowmouse did not have user_data reference back to Ada";
     end Get_Below_Mouse;
 
 
@@ -442,7 +445,8 @@ package body FLTK.Event is
         end if;
         return Actual_Focus;
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Widget returned by Fl::focus did not have user_data reference back to Ada";
     end Get_Focus;
 
 
diff --git a/body/fltk-file_choosers.adb b/body/fltk-file_choosers.adb
index 5662f8a..9345eee 100644
--- a/body/fltk-file_choosers.adb
+++ b/body/fltk-file_choosers.adb
@@ -967,7 +967,8 @@ package body FLTK.File_Choosers is
         end if;
         return Ada_Obj;
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Fl_File_Chooser::add_extra returned Widget with no user_data reference back to Ada";
     end Eject_Extra;
 
 
@@ -1058,7 +1059,9 @@ package body FLTK.File_Choosers is
         pragma Assert (Ret in 0 .. 1);
         return Boolean'Val (Ret);
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Fl_File_Chooser::preview returned unexpected int value of " &
+        Interfaces.C.int'Image (Ret);
     end Has_Preview;
 
 
diff --git a/body/fltk-filenames.adb b/body/fltk-filenames.adb
index 7674323..40645de 100644
--- a/body/fltk-filenames.adb
+++ b/body/fltk-filenames.adb
@@ -170,7 +170,9 @@ package body FLTK.Filenames is
             (Result in Comparison'Pos (Comparison'First) .. Comparison'Pos (Comparison'Last));
         return Comparison'Val (Result);
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Wrapper of fl_alphasort returned unexpected int value of " &
+        Interfaces.C.int'Image (Result);
     end Alpha_Sort;
 
 
@@ -185,7 +187,9 @@ package body FLTK.Filenames is
             (Result in Comparison'Pos (Comparison'First) .. Comparison'Pos (Comparison'Last));
         return Comparison'Val (Result);
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Wrapper of fl_casealphasort returned unexpected int value of " &
+        Interfaces.C.int'Image (Result);
     end Case_Alpha_Sort;
 
 
@@ -200,7 +204,9 @@ package body FLTK.Filenames is
             (Result in Comparison'Pos (Comparison'First) .. Comparison'Pos (Comparison'Last));
         return Comparison'Val (Result);
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Wrapper of fl_numericsort returned unexpected int value of " &
+        Interfaces.C.int'Image (Result);
     end Numeric_Sort;
 
 
@@ -215,7 +221,9 @@ package body FLTK.Filenames is
             (Result in Comparison'Pos (Comparison'First) .. Comparison'Pos (Comparison'Last));
         return Comparison'Val (Result);
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Wrapper of fl_casenumericsort returned unexpected int value of " &
+        Interfaces.C.int'Image (Result);
     end Case_Numeric_Sort;
 
 
@@ -286,7 +294,8 @@ package body FLTK.Filenames is
             pragma Assert (Result = 1);
         end if;
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "fl_open_uri returned unexpected int value of " & Interfaces.C.int'Image (Result);
     end Open_URI;
 
 
diff --git a/body/fltk-static.adb b/body/fltk-static.adb
index 56b30c0..5912a3f 100644
--- a/body/fltk-static.adb
+++ b/body/fltk-static.adb
@@ -915,7 +915,8 @@ package body FLTK.Static is
         end if;
         return Actual_First;
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Widget returned by Fl::first_window did not have user_data reference back to Ada";
     end Get_First_Window;
 
 
@@ -940,7 +941,8 @@ package body FLTK.Static is
         end if;
         return Actual_Next;
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Widget returned by Fl::next_window did not have user_data reference back to Ada";
     end Get_Next_Window;
 
 
@@ -957,7 +959,8 @@ package body FLTK.Static is
         end if;
         return Actual_Modal;
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Widget returned by Fl::modal did not have user_data reference back to Ada";
     end Get_Top_Modal;
 
 
@@ -976,7 +979,8 @@ package body FLTK.Static is
         end if;
         return Actual_Queue;
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Widget returned by Fl::readqueue did not have user_data reference back to Ada";
     end Read_Queue;
 
 
diff --git a/body/fltk-tooltips.adb b/body/fltk-tooltips.adb
index ccdb649..9c7d9ad 100644
--- a/body/fltk-tooltips.adb
+++ b/body/fltk-tooltips.adb
@@ -189,7 +189,8 @@ package body FLTK.Tooltips is
         end if;
         return Actual_Widget;
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Widget returned by Fl_Tooltip::current did not have user_data reference back to Ada";
     end Get_Target;
 
 
diff --git a/body/fltk-widgets-groups-browsers-textline-file.adb b/body/fltk-widgets-groups-browsers-textline-file.adb
index e45396c..5585b6d 100644
--- a/body/fltk-widgets-groups-browsers-textline-file.adb
+++ b/body/fltk-widgets-groups-browsers-textline-file.adb
@@ -406,7 +406,9 @@ package body FLTK.Widgets.Groups.Browsers.Textline.File is
         pragma Assert (Code in File_Kind'Pos (File_Kind'First) .. File_Kind'Pos (File_Kind'Last));
         return File_Kind'Val (Code);
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Fl_File_Browser::filetype returned unexpected int value of " &
+        Interfaces.C.int'Image (Code);
     end Get_File_Kind;
 
 
diff --git a/body/fltk-widgets-groups-browsers-textline.adb b/body/fltk-widgets-groups-browsers-textline.adb
index b7b3077..744315f 100644
--- a/body/fltk-widgets-groups-browsers-textline.adb
+++ b/body/fltk-widgets-groups-browsers-textline.adb
@@ -625,7 +625,8 @@ package body FLTK.Widgets.Groups.Browsers.Textline is
             pragma Assert (Code = 1);
         end if;
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Fl_Browser::load returned unexpected int value of " & Interfaces.C.int'Image (Code);
     end Load;
 
 
@@ -797,7 +798,8 @@ package body FLTK.Widgets.Groups.Browsers.Textline is
         pragma Assert (Code in 0 .. 1);
         return Boolean'Val (Code);
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Fl_Browser::select returned unexpected int value of " & Interfaces.C.int'Image (Code);
     end Set_Select;
 
 
@@ -813,7 +815,8 @@ package body FLTK.Widgets.Groups.Browsers.Textline is
     begin
         pragma Assert (Code in 0 .. 1);
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Fl_Browser::select returned unexpected int value of " & Interfaces.C.int'Image (Code);
     end Set_Select;
 
 
@@ -829,7 +832,8 @@ package body FLTK.Widgets.Groups.Browsers.Textline is
         pragma Assert (Code in 0 .. 1);
         return Boolean'Val (Code);
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Fl_Browser::selected returned unexpected int value of " & Interfaces.C.int'Image (Code);
     end Is_Selected;
 
 
@@ -872,7 +876,8 @@ package body FLTK.Widgets.Groups.Browsers.Textline is
         pragma Assert (Code in 0 .. 1);
         return Boolean'Val (Code);
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Fl_Browser::displayed returned unexpected int value of " & Interfaces.C.int'Image (Code);
     end Is_Displayed;
 
 
@@ -1126,7 +1131,9 @@ package body FLTK.Widgets.Groups.Browsers.Textline is
         pragma Assert (Code in 0 .. 1);
         return Boolean'Val (Code);
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Dispatched item_selected function returned unexpected int value of " &
+        Interfaces.C.int'Image (Code);
     end Item_Selected;
 
 
diff --git a/body/fltk-widgets-groups-browsers.adb b/body/fltk-widgets-groups-browsers.adb
index 36b9f2f..dde3fe7 100644
--- a/body/fltk-widgets-groups-browsers.adb
+++ b/body/fltk-widgets-groups-browsers.adb
@@ -794,7 +794,8 @@ package body FLTK.Widgets.Groups.Browsers is
         pragma Assert (Code in 0 .. 1);
         return Boolean'Val (Code);
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Fl_Browser_::select returned unexpected int value of " & Interfaces.C.int'Image (Code);
     end Set_Select;
 
 
@@ -812,7 +813,8 @@ package body FLTK.Widgets.Groups.Browsers is
     begin
         pragma Assert (Code in 0 .. 1);
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Fl_Browser_::select returned unexpected int value of " & Interfaces.C.int'Image (Code);
     end Set_Select;
 
 
@@ -830,7 +832,9 @@ package body FLTK.Widgets.Groups.Browsers is
         pragma Assert (Code in 0 .. 1);
         return Boolean'Val (Code);
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Fl_Browser_::select_only returned unexpected int value of " &
+        Interfaces.C.int'Image (Code);
     end Select_Only;
 
 
@@ -846,7 +850,9 @@ package body FLTK.Widgets.Groups.Browsers is
     begin
         pragma Assert (Code in 0 .. 1);
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Fl_Browser_::select_only returned unexpected int value of " &
+        Interfaces.C.int'Image (Code);
     end Select_Only;
 
 
@@ -870,7 +876,9 @@ package body FLTK.Widgets.Groups.Browsers is
         pragma Assert (Code in 0 .. 1);
         return Boolean'Val (Code);
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Fl_Browser_::deselect returned unexpected int value of " &
+        Interfaces.C.int'Image (Code);
     end Deselect;
 
 
@@ -884,7 +892,9 @@ package body FLTK.Widgets.Groups.Browsers is
     begin
         pragma Assert (Code in 0 .. 1);
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Fl_Browser_::deselect returned unexpected int value of " &
+        Interfaces.C.int'Image (Code);
     end Deselect;
 
 
@@ -907,7 +917,9 @@ package body FLTK.Widgets.Groups.Browsers is
         pragma Assert (Code in 0 .. 1);
         return Boolean'Val (Code);
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Fl_Browser_::displayed returned unexpected int value of " &
+        Interfaces.C.int'Image (Code);
     end Is_Displayed;
 
 
diff --git a/body/fltk-widgets-groups-color_choosers.adb b/body/fltk-widgets-groups-color_choosers.adb
index 15f34ed..fdb2f04 100644
--- a/body/fltk-widgets-groups-color_choosers.adb
+++ b/body/fltk-widgets-groups-color_choosers.adb
@@ -262,7 +262,9 @@ package body FLTK.Widgets.Groups.Color_Choosers is
     begin
         pragma Assert (Result in 0 .. 1);
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Fl_Color_Chooser::rgb returned unexpected int value of " &
+        Interfaces.C.int'Image (Result);
     end Set_RGB;
 
 
@@ -279,7 +281,9 @@ package body FLTK.Widgets.Groups.Color_Choosers is
     begin
         return Boolean'Val (Result);
     exception
-    when Constraint_Error => raise Internal_FLTK_Error;
+    when Constraint_Error => raise Internal_FLTK_Error with
+        "Fl_Color_Chooser::rgb returned unexpected int value of " &
+        Interfaces.C.int'Image (Result);
     end Set_RGB;
 
 
@@ -321,7 +325,9 @@ package body FLTK.Widgets.Groups.Color_Choosers is
     begin
         pragma Assert (Result in 0 .. 1);
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Fl_Color_Chooser:hsv returned unexpected int value of " &
+        Interfaces.C.int'Image (Result);
     end Set_HSV;
 
 
@@ -338,7 +344,9 @@ package body FLTK.Widgets.Groups.Color_Choosers is
     begin
         return Boolean'Val (Result);
     exception
-    when Constraint_Error => raise Internal_FLTK_Error;
+    when Constraint_Error => raise Internal_FLTK_Error with
+        "Fl_Color_Chooser::hsv returned unexpected int value of " &
+        Interfaces.C.int'Image (Result);
     end Set_HSV;
 
 
diff --git a/body/fltk-widgets-groups-help_views.adb b/body/fltk-widgets-groups-help_views.adb
index 6435c0f..afcec47 100644
--- a/body/fltk-widgets-groups-help_views.adb
+++ b/body/fltk-widgets-groups-help_views.adb
@@ -260,7 +260,9 @@ package body FLTK.Widgets.Groups.Help_Views is
             return Ada_Help_View.Hilda;
         end if;
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Fl_Help_View::link callback hook received Widget with no user_data reference " &
+        "back to Ada";
     end Link_Callback_Hook;
 
 
@@ -451,7 +453,9 @@ package body FLTK.Widgets.Groups.Help_Views is
             pragma Assert (Code = 0);
         end if;
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Fl_Help_View::load returned unexpected int value of " &
+        Interfaces.C.int'Image (Code);
     end Load;
 
 
diff --git a/body/fltk-widgets-groups-tabbed.adb b/body/fltk-widgets-groups-tabbed.adb
index 360b824..7ed9ea9 100644
--- a/body/fltk-widgets-groups-tabbed.adb
+++ b/body/fltk-widgets-groups-tabbed.adb
@@ -214,7 +214,8 @@ package body FLTK.Widgets.Groups.Tabbed is
         end if;
         return Actual_Widget;
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Fl_Tabs::push returned Widget with no user_data reference back to Ada";
     end Get_Push;
 
 
@@ -240,7 +241,8 @@ package body FLTK.Widgets.Groups.Tabbed is
         end if;
         return Actual_Widget;
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Fl_Tabs::value returned Widget with no user_data reference back to Ada";
     end Get_Visible;
 
 
@@ -268,7 +270,8 @@ package body FLTK.Widgets.Groups.Tabbed is
         end if;
         return Actual_Widget;
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Fl_Tabs::which returned Widget with no user_data reference back to Ada";
     end Get_Which;
 
 
diff --git a/body/fltk-widgets-groups-windows-double-cairo.adb b/body/fltk-widgets-groups-windows-double-cairo.adb
index 897c206..a605c49 100644
--- a/body/fltk-widgets-groups-windows-double-cairo.adb
+++ b/body/fltk-widgets-groups-windows-double-cairo.adb
@@ -85,7 +85,8 @@ package body FLTK.Widgets.Groups.Windows.Double.Cairo is
             Ada_Object.My_Func (Cairo_Window (Ada_Object.all), Storage.To_Address (Cairo_Addr));
         end if;
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Fl_Cairo_Window draw hook received Widget with no user_data reference back to Ada";
     end Cairo_Draw_Hook;
 
 
diff --git a/body/fltk-widgets-groups-wizards.adb b/body/fltk-widgets-groups-wizards.adb
index eb604a1..06aa1e9 100644
--- a/body/fltk-widgets-groups-wizards.adb
+++ b/body/fltk-widgets-groups-wizards.adb
@@ -193,7 +193,8 @@ package body FLTK.Widgets.Groups.Wizards is
         end if;
         return Actual_Widget;
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Fl_Wizard::value returned Widget with no user_data reference back to Ada";
     end Get_Visible;
 
 
diff --git a/body/fltk-widgets-groups.adb b/body/fltk-widgets-groups.adb
index 3b2e287..281d273 100644
--- a/body/fltk-widgets-groups.adb
+++ b/body/fltk-widgets-groups.adb
@@ -374,7 +374,8 @@ package body FLTK.Widgets.Groups is
         Actual_Widget := Widget_Convert.To_Pointer (Storage.To_Address (Widget_Ptr));
         return (Data => Actual_Widget);
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Fl_Group::child returned Widget with no user_data reference back to Ada";
     end Child;
 
 
@@ -471,11 +472,15 @@ package body FLTK.Widgets.Groups is
 
     function Get_Clip_Mode
            (This : in Group)
-        return Clip_Mode is
+        return Clip_Mode
+    is
+        Result : Interfaces.C.unsigned := fl_group_get_clip_children (This.Void_Ptr);
     begin
-        return Clip_Mode'Val (fl_group_get_clip_children (This.Void_Ptr));
+        return Clip_Mode'Val (Result);
     exception
-    when Constraint_Error => raise Internal_FLTK_Error;
+    when Constraint_Error => raise Internal_FLTK_Error with
+        "Fl_Group::clip_children returned unexpected unsigned int value of " &
+        Interfaces.C.unsigned'Image (Result);
     end Get_Clip_Mode;
 
 
@@ -511,7 +516,8 @@ package body FLTK.Widgets.Groups is
         end if;
         return Actual_Widget;
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Fl_Group::resizable returned Widget with no user_data reference back to Ada";
     end Get_Resizable;
 
 
@@ -558,7 +564,8 @@ package body FLTK.Widgets.Groups is
         end if;
         return Actual_Group;
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Fl_Group::current returned Widget with no user_data reference back to Ada";
     end Get_Current;
 
 
diff --git a/body/fltk-widgets-inputs-text-file.adb b/body/fltk-widgets-inputs-text-file.adb
index c7e4919..18b227f 100644
--- a/body/fltk-widgets-inputs-text-file.adb
+++ b/body/fltk-widgets-inputs-text-file.adb
@@ -245,7 +245,9 @@ package body FLTK.Widgets.Inputs.Text.File is
     begin
         pragma Assert (Result /= 0);
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Fl_File_Input::value returned unexpected int value of " &
+        Interfaces.C.int'Image (Result);
     end Set_Value;
 
 
diff --git a/body/fltk-widgets-inputs.adb b/body/fltk-widgets-inputs.adb
index 0d3a3fe..ab83121 100644
--- a/body/fltk-widgets-inputs.adb
+++ b/body/fltk-widgets-inputs.adb
@@ -414,7 +414,9 @@ package body FLTK.Widgets.Inputs is
     begin
         pragma Assert (Result in 0 .. 1);
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Fl_Input_::copy returned unexpected int value of " &
+        Interfaces.C.int'Image (Result);
     end Copy;
 
 
@@ -429,7 +431,9 @@ package body FLTK.Widgets.Inputs is
         pragma Assert (Result in 0 .. 1);
         return Boolean'Val (Result);
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Fl_Input_::copy returned unexpected int value of " &
+        Interfaces.C.int'Image (Result);
     end Copy;
 
 
diff --git a/body/fltk-widgets-positioners.adb b/body/fltk-widgets-positioners.adb
index 053d731..68532a2 100644
--- a/body/fltk-widgets-positioners.adb
+++ b/body/fltk-widgets-positioners.adb
@@ -284,7 +284,9 @@ package body FLTK.Widgets.Positioners is
     begin
         pragma Assert (Result in 0 .. 1);
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Fl_Positioner::value returned unexpected int value of " &
+        Interfaces.C.int'Image (Result);
     end Set_Coords;
 
 
@@ -300,7 +302,9 @@ package body FLTK.Widgets.Positioners is
     begin
         return Boolean'Val (Result);
     exception
-    when Constraint_Error => raise Internal_FLTK_Error;
+    when Constraint_Error => raise Internal_FLTK_Error with
+        "Fl_Positioner::value returned unexpected int value of " &
+        Interfaces.C.int'Image (Result);
     end Set_Coords;
 
 
@@ -375,7 +379,9 @@ package body FLTK.Widgets.Positioners is
     begin
         pragma Assert (Result in 0 .. 1);
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Fl_Positioner::xvalue returned unexpected int value of " &
+        Interfaces.C.int'Image (Result);
     end Set_Ecks;
 
 
@@ -390,7 +396,9 @@ package body FLTK.Widgets.Positioners is
     begin
         return Boolean'Val (Result);
     exception
-    when Constraint_Error => raise Internal_FLTK_Error;
+    when Constraint_Error => raise Internal_FLTK_Error with
+        "Fl_Positioner::xvalue returned unexpected int value of " &
+        Interfaces.C.int'Image (Result);
     end Set_Ecks;
 
 
@@ -465,7 +473,9 @@ package body FLTK.Widgets.Positioners is
     begin
         pragma Assert (Result in 0 .. 1);
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Fl_Positioner::yvalue returned unexpected int value of " &
+        Interfaces.C.int'Image (Result);
     end Set_Why;
 
 
@@ -480,7 +490,9 @@ package body FLTK.Widgets.Positioners is
     begin
         return Boolean'Val (Result);
     exception
-    when Constraint_Error => raise Internal_FLTK_Error;
+    when Constraint_Error => raise Internal_FLTK_Error with
+        "Fl_Positioner::yvalue returned unexpected int value of " &
+        Interfaces.C.int'Image (Result);
     end Set_Why;
 
 
@@ -519,17 +531,21 @@ package body FLTK.Widgets.Positioners is
            (This       : in out Positioner;
             Event      : in     Event_Kind;
             X, Y, W, H : in     Integer)
-        return Event_Outcome is
-    begin
-        return Event_Outcome'Val (fl_positioner_handle2
+        return Event_Outcome
+    is
+        Result : Interfaces.C.int := fl_positioner_handle2
            (This.Void_Ptr,
             Event_Kind'Pos (Event),
             Interfaces.C.int (X),
             Interfaces.C.int (Y),
             Interfaces.C.int (W),
-            Interfaces.C.int (H)));
+            Interfaces.C.int (H));
+    begin
+        return Event_Outcome'Val (Result);
     exception
-    when Constraint_Error => raise Internal_FLTK_Error;
+    when Constraint_Error => raise Internal_FLTK_Error with
+        "Fl_Positioner::handle returned unexpected int value of " &
+        Interfaces.C.int'Image (Result);
     end Handle;
 
 
diff --git a/body/fltk-widgets-valuators-dials.adb b/body/fltk-widgets-valuators-dials.adb
index 6dc9e69..93a636a 100644
--- a/body/fltk-widgets-valuators-dials.adb
+++ b/body/fltk-widgets-valuators-dials.adb
@@ -270,17 +270,21 @@ package body FLTK.Widgets.Valuators.Dials is
            (This       : in out Dial;
             Event      : in     Event_Kind;
             X, Y, W, H : in     Integer)
-        return Event_Outcome is
-    begin
-        return Event_Outcome'Val (fl_dial_handle2
+        return Event_Outcome
+    is
+        Result : Interfaces.C.int := fl_dial_handle2
            (This.Void_Ptr,
             Event_Kind'Pos (Event),
             Interfaces.C.int (X),
             Interfaces.C.int (Y),
             Interfaces.C.int (W),
-            Interfaces.C.int (H)));
+            Interfaces.C.int (H));
+    begin
+        return Event_Outcome'Val (Result);
     exception
-    when Constraint_Error => raise Internal_FLTK_Error;
+    when Constraint_Error => raise Internal_FLTK_Error with
+        "Fl_Dial::handle returned unexpected int value of " &
+        Interfaces.C.int'Image (Result);
     end Handle;
 
 
diff --git a/body/fltk-widgets.adb b/body/fltk-widgets.adb
index a312641..4518491 100644
--- a/body/fltk-widgets.adb
+++ b/body/fltk-widgets.adb
@@ -800,7 +800,8 @@ package body FLTK.Widgets is
         end if;
         return Actual_Parent;
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Widget returned by Fl_Widget::parent has no user_data reference back to Ada";
     end Parent;
 
 
@@ -836,7 +837,8 @@ package body FLTK.Widgets is
         end if;
         return Actual_Window;
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Widget returned by Fl_Widget::window has no user_data reference back to Ada";
     end Nearest_Window;
 
 
@@ -854,7 +856,8 @@ package body FLTK.Widgets is
         end if;
         return Actual_Window;
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Widget returned by Fl_Widget::top_window has no user_data reference back to Ada";
     end Top_Window;
 
 
@@ -876,7 +879,8 @@ package body FLTK.Widgets is
         end if;
         return Actual_Window;
     exception
-    when Chk.Assertion_Error => raise Internal_FLTK_Error;
+    when Chk.Assertion_Error => raise Internal_FLTK_Error with
+        "Widget returned by Fl_Widget::top_window_offset has no user_data reference back to Ada";
     end Top_Window_Offset;
 
 
@@ -1269,10 +1273,14 @@ package body FLTK.Widgets is
             return Interfaces.C.int;
         for my_handle'Address use This.Handle_Ptr;
         pragma Import (Ada, my_handle);
+
+        Result : Interfaces.C.int := my_handle (This.Void_Ptr, Event_Kind'Pos (Event));
     begin
-        return Event_Outcome'Val (my_handle (This.Void_Ptr, Event_Kind'Pos (Event)));
+        return Event_Outcome'Val (Result);
     exception
-    when Constraint_Error => raise Internal_FLTK_Error;
+    when Constraint_Error => raise Internal_FLTK_Error with
+        "Dispatched handle function returned unexpected int value of " &
+        Interfaces.C.int'Image (Result);
     end Handle;