More additions by @tomet slightly modified to match the library's style

drawings.cxx

@@ -11,6 +11,12 @@ void go_fltk_color(unsigned int color) {
 void go_fltk_set_draw_font(int font, int size) {
   fl_font((Fl_Font)font, size);
 }
+int go_fltk_draw_font() {
+	return fl_font();
+}
+int go_fltk_draw_font_size() {
+	return fl_size();
+}
 void go_fltk_draw(const char* text, int x, int y, int w, int h, unsigned int align) {
   fl_draw(text, x, y, w, h, (Fl_Align)align);
 }
@@ -70,7 +76,7 @@ void go_fltk_draw_arrow(int x, int y, int w, int h, int arr, int orient, unsigne
 	Fl_Rect r{x, y, w, h};
 	fl_draw_arrow(r, (Fl_Arrow_Type)arr, (Fl_Orientation)orient, color);
 }
-
+
 void go_fltk_rect_with_color(int x, int y, int w, int h, unsigned int c) {
     fl_rect(x, y, w, h, c);
 }
@@ -455,4 +461,4 @@ void go_fltk_draw_text2(const char *str, int x, int y, int w, int h, int align)
 
 void go_fltk_draw_check(int x, int y, int w, int h, unsigned int col) {
     fl_draw_check(Fl_Rect(x, y, w, h), (Fl_Color)col);
-}
+}

drawings.go

@@ -26,6 +26,10 @@ func SetDrawFont(font Font, size int) {
 	C.go_fltk_set_draw_font(C.int(font), C.int(size))
 }
 
+func DrawFont() (Font, int) {
+	return Font(C.go_fltk_draw_font()), int(C.go_fltk_draw_font_size())
+}
+
 func PushClip(x, y, w, h int) {
 	C.go_fltk_push_clip(C.int(x), C.int(y), C.int(w), C.int(h))
 }
@@ -65,11 +69,11 @@ func DrawRectf(x, y, w, h int) {
 func DrawRectfWithColor(x, y, w, h int, col Color) {
 	C.go_fltk_rectf_with_color(C.int(x), C.int(y), C.int(w), C.int(h), C.uint(col))
 }
-
-func DrawArrow(x, y, w, h int, arr ArrowType, orient Orientation, col Color) {
-	C.go_fltk_draw_arrow(C.int(x), C.int(y), C.int(w), C.int(h), C.int(arr), C.int(orient), C.uint(col))
-}
-
+
+func DrawArrow(x, y, w, h int, arr ArrowType, orient Orientation, col Color) {
+	C.go_fltk_draw_arrow(C.int(x), C.int(y), C.int(w), C.int(h), C.int(arr), C.int(orient), C.uint(col))
+}
+
 func DrawLine(x, y, x1, y1 int) {
 	C.go_fltk_line(C.int(x), C.int(y), C.int(x1), C.int(y1))
 }

drawings.h

@@ -8,6 +8,8 @@ extern "C" {
 
   extern void go_fltk_color(unsigned int color);
   extern void go_fltk_set_draw_font(int font, int size);
+  extern int go_fltk_draw_font();
+  extern int go_fltk_draw_font_size();   
   extern void go_fltk_draw(const char* text, int x, int y, int w, int h, unsigned int align);
   extern void go_fltk_draw_box(int boxType, int x, int y, int w, int h, unsigned int color);
   extern void go_fltk_push_clip(int x, int y, int w, int h);
@@ -26,8 +28,8 @@ extern "C" {
   extern void go_fltk_rectf(int x, int y, int w, int h);
   extern void go_fltk_rectf_with_color(int x, int y, int w, int h, unsigned int c);
   extern void go_fltk_rectf_with_rgb(int x, int y, int w, int h, unsigned char r, unsigned char g,
-                          unsigned char b);
-  extern void go_fltk_draw_arrow(int x, int y, int w, int h, int arr, int orient, unsigned int color);
+                          unsigned char b);
+  extern void go_fltk_draw_arrow(int x, int y, int w, int h, int arr, int orient, unsigned int color);
   extern void go_fltk_line(int x, int y, int x1, int y1);
   extern void go_fltk_line2(int x, int y, int x1, int y1, int x2, int y2);
   extern void go_fltk_loop(int x, int y, int x1, int y1, int x2, int y2);

enumerations.cxx

@@ -131,6 +131,9 @@ const int go_FL_F9 = FL_F + 9;
 const int go_FL_F10 = FL_F + 10;
 const int go_FL_F11 = FL_F + 11;
 const int go_FL_F12 = FL_F + 12;
+const int go_FL_DELETE = FL_Delete;
+const int go_FL_BACKSPACE = FL_BackSpace;
+const int go_FL_INSERT = FL_Insert;
 
 const int go_FL_RGB = FL_RGB;
 const int go_FL_INDEX = FL_INDEX;

enumerations.go

@@ -46,15 +46,15 @@ var (
 type Orientation int
 
 var (
-	ORIENT_NONE   = Orientation(C.go_FL_ORIENT_NONE)
-	ORIENT_RIGHT  = Orientation(C.go_FL_ORIENT_RIGHT)
-	ORIENT_NE     = Orientation(C.go_FL_ORIENT_NE)
-	ORIENT_UP     = Orientation(C.go_FL_ORIENT_UP)
-	ORIENT_NW     = Orientation(C.go_FL_ORIENT_NW)
-	ORIENT_LEFT   = Orientation(C.go_FL_ORIENT_LEFT)
-	ORIENT_SW     = Orientation(C.go_FL_ORIENT_SW)
-	ORIENT_DOWN   = Orientation(C.go_FL_ORIENT_DOWN)
-	ORIENT_SE     = Orientation(C.go_FL_ORIENT_SE)
+	ORIENT_NONE  = Orientation(C.go_FL_ORIENT_NONE)
+	ORIENT_RIGHT = Orientation(C.go_FL_ORIENT_RIGHT)
+	ORIENT_NE    = Orientation(C.go_FL_ORIENT_NE)
+	ORIENT_UP    = Orientation(C.go_FL_ORIENT_UP)
+	ORIENT_NW    = Orientation(C.go_FL_ORIENT_NW)
+	ORIENT_LEFT  = Orientation(C.go_FL_ORIENT_LEFT)
+	ORIENT_SW    = Orientation(C.go_FL_ORIENT_SW)
+	ORIENT_DOWN  = Orientation(C.go_FL_ORIENT_DOWN)
+	ORIENT_SE    = Orientation(C.go_FL_ORIENT_SE)
 )
 
 type BoxType int
@@ -387,4 +387,7 @@ var (
 	F10       = int(C.go_FL_F10)
 	F11       = int(C.go_FL_F11)
 	F12       = int(C.go_FL_F12)
+	DELETE    = int(C.go_FL_DELETE)
+	BACKSPACE = int(C.go_FL_BACKSPACE)
+	INSERT    = int(C.go_FL_INSERT)
 )

enumerations.h

@@ -130,6 +130,9 @@ extern "C" {
   extern const int go_FL_F10;
   extern const int go_FL_F11;
   extern const int go_FL_F12;
+  extern const int go_FL_DELETE;
+  extern const int go_FL_BACKSPACE;
+  extern const int go_FL_INSERT;  
 
   extern const int go_FL_RGB;
   extern const int go_FL_INDEX;

event_handler.h

@@ -39,7 +39,7 @@ class EventHandler : public BaseWidget, public WidgetWithEventHandler, public Wi
     if (m_eventHandlerId >= 0) {
       const int ret = _go_eventHandler(m_eventHandlerId, event);
       if (ret != 0) {
-	return ret;
+        return ret;
       }
     }
     return BaseWidget::handle(event);

image.go

@@ -198,6 +198,24 @@ func NewRgbImageFromSvg(img *SvgImage) (*RgbImage) {
 	return rgbImage
 }
 
+func NewRgbImageFromPng(img *PngImage) (*RgbImage) {
+	rgbImage := &RgbImage{}
+	rgbImage.image = img.image
+	return rgbImage
+}
+
+func NewRgbImageFromBmp(img *BmpImage) (*RgbImage) {
+	rgbImage := &RgbImage{}
+	rgbImage.image = img.image
+	return rgbImage
+}
+
+func NewRgbImageFromJpeg(img *JpegImage) (*RgbImage) {
+	rgbImage := &RgbImage{}
+	rgbImage.image = img.image
+	return rgbImage
+}
+
 func NewRgbImageFromImage(image goimage.Image) (*RgbImage, error) {
 	rgbImage := &RgbImage{}
 	var w, h, stride, depth int

text.cxx

@@ -7,12 +7,20 @@
 #include <FL/Fl_Text_Buffer.H>
 
 #include "event_handler.h"
+#include "_cgo_export.h"
 
 
+// --- Text Display ---
+
 class GText_Display : public EventHandler<Fl_Text_Display> {
 public:
-  GText_Display(int x, int y, int w, int h, const char* label)
-    : EventHandler<Fl_Text_Display>(x, y, w, h, label) {}
+  GText_Display(int x, int y, int w, int h, const char *label)
+      : EventHandler<Fl_Text_Display>(x, y, w, h, label) {}
+
+  // make xy_to_position() public
+  int xy_to_position(int x, int y) {
+    return EventHandler<Fl_Text_Display>::xy_to_position(x, y);
+  }  
 };
 
 GText_Display *go_fltk_new_TextDisplay(int x, int y, int w, int h, const char *text) {
@@ -27,6 +35,14 @@ void go_fltk_TextDisplay_set_wrap_mode(Fl_Text_Display *d, int wrap, int wrapMar
   d->wrap_mode(wrap, wrapMargin);
 }
 
+int go_fltk_TextDisplay_xy_to_position(Fl_Text_Display *d, int x, int y) {
+  return ((GText_Display*) d)->xy_to_position(x, y);
+}
+
+int go_fltk_TextDisplay_position_to_xy(Fl_Text_Display *d, int pos, int *x, int *y) {
+  return d->position_to_xy(pos, x, y);
+}
+
 int go_fltk_TextDisplay_move_right(Fl_Text_Display *d) {
   return d->move_right();
 }
@@ -47,6 +63,10 @@ void go_fltk_TextDisplay_show_insert_position(Fl_Text_Display *d) {
   d->show_insert_position();
 }
 
+void go_fltk_TextDisplay_hide_cursor(Fl_Text_Display *d) {
+  d->hide_cursor();
+}
+
 unsigned int go_fltk_TextDisplay_text_color(Fl_Text_Display *d) {
   return d->textcolor();
 }
@@ -83,6 +103,8 @@ void go_fltk_TextDisplay_overstrike(Fl_Text_Display *d, const char* text) {
   d->overstrike(text);
 }
 
+// --- Text Editor ---
+
 class GText_Editor : public EventHandler<Fl_Text_Editor> {
 public:
   GText_Editor(int x, int y, int w, int h, const char* label)
@@ -117,6 +139,13 @@ void go_fltk_TextEditor_select_all(Fl_Text_Editor *e) {
   Fl_Text_Editor::kf_select_all(0, e);
 }
 
+// --- Text Buffer ---
+
+void modify_callback_handler(int pos, int nInserted, int nDeleted, int nRestyled, const char *deletedText, void *cbArg) {
+  uintptr_t id = (uintptr_t)cbArg;
+  _go_modifyCallbackHandler(id, pos, nInserted, nDeleted, nRestyled, (char*)deletedText);
+}
+
 Fl_Text_Buffer *go_fltk_new_TextBuffer(void) {
   return new Fl_Text_Buffer;
 }
@@ -125,6 +154,10 @@ void go_fltk_TextBuffer_delete(Fl_Text_Buffer* b) {
   delete b;
 }
 
+void go_fltk_TextBuffer_add_modify_callback(Fl_Text_Buffer *b, uintptr_t handlerId) {
+	b->add_modify_callback(modify_callback_handler, (void*)handlerId);
+}
+
 void go_fltk_TextBuffer_set_text(Fl_Text_Buffer *b, const char *txt) {
   b->text(txt);
 }
@@ -133,6 +166,22 @@ void go_fltk_TextBuffer_append(Fl_Text_Buffer *b, const char *txt) {
   b->append(txt);
 }
 
+unsigned int go_fltk_TextBuffer_char_at(Fl_Text_Buffer *b, int pos) {
+  return b->char_at(pos);
+}
+
+int go_fltk_TextBuffer_next_char(Fl_Text_Buffer *b, int ix) {
+  return b->next_char(ix);
+}
+
+int go_fltk_TextBuffer_prev_char(Fl_Text_Buffer *b, int ix) {
+  return b->prev_char(ix);
+}
+
+int go_fltk_TextBuffer_length(Fl_Text_Buffer *b) {
+  return b->length();
+}
+
 const char *go_fltk_TextBuffer_text(Fl_Text_Buffer *b) {
   return b->text();
 }
@@ -202,4 +251,4 @@ void go_fltk_TextDisplay_set_highlight_data(Fl_Text_Display *self, Fl_Text_Buffe
         stable[i] = (Fl_Text_Display::Style_Table_Entry){color[i], font[i], fontsz[i], attr[i], bgcolor[i]};                       
     }                                                                                          
     self->highlight_data(sbuff, stable, sz, 'A', 0, 0);                
-}                                                                                              
+}