Could you provide a minimal self-contained testcase?

I wrote the test program which is copied below. 

Here is what I found out: 
1. If the container hierarchy is scroll-window, frame, text-view, then
   scrolling with the mouse wheel or scroll bars works, but programmatic
   scrolling (scroll to iter or mark) does not work.
2. If the container hierarchy is scroll-window, text-view (no frame),
   then everything works OK.

Test program and make file follow:


ztest.cc --------------------------------------------------------------------------------

//  test gtk_text_view for program-controlled scrolling


#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <gtk/gtk.h>


int eventfunc(GtkWidget *widget, GdkEvent *event);
void textview_append(GtkWidget *widget, const char *text);
char * textview_get_line(GtkWidget *widget, int line);

int   currline = 0;
int   Nlines = 100;


int main(int argc, char *argv[])
{
   GtkWidget   *reportwin, *scrollwin, *frame, *textview;
   char        buff[100];

   setenv("GDK_BACKEND","x11",1);
   setenv("GTK_THEME","default",0);

   gtk_init(&argc,&argv);

   reportwin = gtk_window_new(GTK_WINDOW_TOPLEVEL);
   gtk_window_set_title(GTK_WINDOW(reportwin),"report window");
   gtk_window_set_default_size(GTK_WINDOW(reportwin),500,300);
   gtk_window_set_position(GTK_WINDOW(reportwin),GTK_WIN_POS_CENTER_ON_PARENT);
   scrollwin = gtk_scrolled_window_new(0,0);
   gtk_container_add(GTK_CONTAINER(reportwin),scrollwin);
//-------------------------------------------------------------------------------
//   frame = gtk_frame_new(0);
//   gtk_container_add(GTK_CONTAINER(scrollwin),frame);          //  option A FAILS
//   textview = gtk_text_view_new();
//   gtk_container_add(GTK_CONTAINER(frame),textview);
//-------------------------------------------------------------------------------
   textview = gtk_text_view_new();                             //  option B OK
   gtk_container_add(GTK_CONTAINER(scrollwin),textview);
//-------------------------------------------------------------------------------

   gtk_text_view_set_editable(GTK_TEXT_VIEW(textview),0);

   gtk_widget_show_all(reportwin);
   
   g_signal_connect(G_OBJECT(reportwin),"destroy",gtk_main_quit,0);
   g_signal_connect(G_OBJECT(reportwin),"delete-event",gtk_main_quit,0);
   
   gtk_widget_add_events(textview,GDK_BUTTON_PRESS_MASK);
   gtk_widget_add_events(textview,GDK_KEY_PRESS_MASK);
   gtk_widget_add_events(textview,GDK_ENTER_NOTIFY_MASK);
   g_signal_connect(G_OBJECT(textview),"key-press-event",G_CALLBACK(eventfunc),0);
   g_signal_connect(G_OBJECT(textview),"button-press-event",G_CALLBACK(eventfunc),0);
   g_signal_connect(G_OBJECT(textview),"enter-notify-event",G_CALLBACK(eventfunc),0);

   for (int line = 0; line < Nlines; line++) 
   {
      snprintf(buff,100,"%03d The quick brown fox jumps over the lazy dog.\n",line);
      textview_append(textview,buff);
   }

   gtk_main();
   return 0;
}


int eventfunc(GtkWidget *widget, GdkEvent *event)
{
   GdkDisplay        *display;
   GdkWindow         *gdkwin;
   static GdkCursor  *arrowcursor = 0;
   GtkTextIter       iter1;
   int               mpx, mpy, tbx, tby, line, pos, kbkey;
   char              *textline;

   #define TEXT GTK_TEXT_WINDOW_TEXT
   #define VIEW GTK_TEXT_VIEW
   #define ARROW GDK_TOP_LEFT_ARROW
   #define appfontsize 12

   if (! arrowcursor) {
      gdkwin = gtk_widget_get_window(widget);
      display = gdk_window_get_display(gdkwin);
      arrowcursor = gdk_cursor_new_for_display(display,ARROW);
   }

   gdkwin = gtk_text_view_get_window(VIEW(widget),TEXT);
   if (gdkwin) gdk_window_set_cursor(gdkwin,arrowcursor);

   if (event->type == GDK_KEY_PRESS) {
      kbkey = ((GdkEventKey *) event)->keyval;
      printf("keyboard key %d \n",kbkey);
      if (kbkey == GDK_KEY_Up) currline--;
      if (kbkey == GDK_KEY_Down) currline++;
      if (currline < 0) currline = 0;
      if (currline > Nlines-1) currline = Nlines - 1;
      textline = textview_get_line(widget,currline);
      return 1;
   }

   if (event->type == GDK_BUTTON_PRESS) {
      mpx = int(((GdkEventButton *) event)->x);
      mpy = int(((GdkEventButton *) event)->y);
      mpx -= appfontsize / 2;
      if (mpx < 0) mpx = 0;
      gtk_text_view_window_to_buffer_coords(VIEW(widget),TEXT,mpx,mpy,&tbx,&tby);
      gtk_text_view_get_iter_at_location(VIEW(widget),&iter1,tbx,tby);
      line = gtk_text_iter_get_line(&iter1);
      pos = gtk_text_iter_get_line_offset(&iter1);
      printf("click on line %d  position %d \n",line,pos);
      currline = line;
      textline = textview_get_line(widget,currline);
      if (textline) free(textline);
      return 1;
   }
   
   return 0;
}


void textview_append(GtkWidget *widget, const char *text)
{
   GtkTextBuffer  *textBuff;
   GtkTextIter    enditer;
   GtkTextMark    *endmark;
   GtkTextTag     *fontag;

   textBuff = gtk_text_view_get_buffer(GTK_TEXT_VIEW(widget));

   gtk_text_buffer_get_end_iter(textBuff,&enditer);
   endmark = gtk_text_buffer_create_mark(textBuff,"endmark",&enditer,0);

   fontag = gtk_text_buffer_create_tag(textBuff,0,"font","mono 12",0);
   gtk_text_buffer_insert_with_tags(textBuff,&enditer,text,-1,fontag,NULL);

   gtk_text_view_scroll_to_mark(GTK_TEXT_VIEW(widget),endmark,0,0,1,1);

   while (gtk_events_pending()) gtk_main_iteration_do(0);
   return;
}


char * textview_get_line(GtkWidget *widget, int line)
{
   GtkTextBuffer  *textBuff;
   GtkTextIter    iter1, iter2;
   int            nlines;
   char           *textline;

   textBuff = gtk_text_view_get_buffer(GTK_TEXT_VIEW(widget));
   
   nlines = gtk_text_buffer_get_line_count(textBuff);
   if (line < 0 || line >= nlines) return 0;
   
   gtk_text_buffer_get_iter_at_line(textBuff,&iter1,line);
   iter2 = iter1;
   gtk_text_iter_forward_line(&iter2);
   textline = gtk_text_buffer_get_text(textBuff,&iter1,&iter2,0);
   if (! textline) return 0;
   gtk_text_buffer_select_range(textBuff,&iter1,&iter2);
   gtk_text_view_scroll_to_iter(GTK_TEXT_VIEW(widget),&iter1,0,0,1,1);
   gtk_text_view_scroll_to_iter(GTK_TEXT_VIEW(widget),&iter2,0,0,1,1);
   return textline;
}



Makefile: --------------------------------------------------------------------------

CFLAGS = $(CXXFLAGS) -Wall -O0 -c `pkg-config --cflags gtk+-3.0`

ztest: ztest.o
	$(CXX) $(LDFLAGS) -o ztest ztest.o `pkg-config --libs gtk+-3.0`

ztest.o: ztest.cc
	$(CXX) $(CFLAGS) -o ztest.o ztest.cc

I'm pretty sure this is just because ScrolledWindow won't traverse >1 child to get scroll adjustments to sync to.

When adding the TextView, ScrolledWindow.add() finds that it's a GtkScrollable, so the SW syncs its h/v adjustments with the TextView.

Otherwise, when adding the Frame, or any other non-Scrollable, that gets wrapped in the autogenerated ViewPort, then the ScrolledWindow syncs its adjustments with those of the ViewPort, not the nested TextView.

In this case, I can't see why you wouldn't just use Frame > ScrolledWindow > TextView anyway.

-- GitLab Migration Automatic Message --

This bug has been migrated to GNOME's GitLab instance and has been closed from further activity.

You can subscribe and participate further through the new bug through this link to our GitLab instance: https://gitlab.gnome.org/GNOME/gtk/issues/918.