Do not crash if expanded widgets change during arrangement. Fix GTK+ window centering method.

[GB.GTK]
* BUG: Do not crash if expanded widgets change during arrangement.

[GB.GTK3]
* BUG: Remove platform-specific window centering method.
* BUG: Do not crash if expanded widgets change during arrangement.

[GB.QT4]
* BUG: Do not crash if expanded widgets change during arrangement.

[GB.QT5]
* BUG: Do not crash if expanded widgets change during arrangement.

gb.gtk/src/gmainwindow.cpp

@@ -958,19 +958,22 @@ void gMainWindow::center()
 {
 	if (!isTopLevel()) return;
 
+	GdkRectangle rect;
+	int x, y;
+
+	if (!isTopLevel()) return;
+
 	#ifdef GTK3
-		PLATFORM.Window.Center(GTK_WINDOW(border));
+	if (MAIN_platform_is_wayland)
-	#else
+		gtk_window_set_position(GTK_WINDOW(border), GTK_WIN_POS_CENTER_ON_PARENT);
-		GdkRectangle rect;
-		int x, y;
-
-		gDesktop::availableGeometry(screen(), &rect);
-
-		x = rect.x + (rect.width - width()) / 2;
-		y = rect.y + (rect.height - height()) / 2;
-
-		move(x, y);
 	#endif
+
+	gDesktop::availableGeometry(screen(), &rect);
+
+	x = rect.x + (rect.width - width()) / 2;
+	y = rect.y + (rect.height - height()) / 2;
+
+	move(x, y);
 }
 
 bool gMainWindow::isModal() const
@@ -991,13 +994,13 @@ void gMainWindow::showModal()
 	setType(GTK_WINDOW_TOPLEVEL);
 
 	gtk_window_set_modal(GTK_WINDOW(border), true);
-  center();
 	setTransientFor();
 
 	save = _current;
 	_current = this;
 
 	show();
+  center();
 	gtk_grab_add(border);
 	gApplication::enterLoop(this);
 

gb.gtk3/src/gb.gtk.platform.h

@@ -42,7 +42,6 @@ typedef
 		
 		struct {
 			long (*GetId)(GdkWindow *);
-			void (*Center)(GtkWindow *);
 		} Window;
 		
 		struct {

gb.gtk3/src/wayland/main.c

@@ -47,12 +47,6 @@ static long window_get_id(GdkWindow *window)
 	return 0;
 }
 
-static void window_center(GtkWindow *window)
-{
-	fprintf(stderr, "window_center\n");
-	gtk_window_set_position(window, GTK_WIN_POS_CENTER_ON_PARENT);
-}
-
 //-------------------------------------------------------------------------
 
 bool desktop_has_system_tray()

gb.gtk3/src/x11/main.c

@@ -58,26 +58,6 @@ static long window_get_id(GdkWindow *window)
 	return window ? GDK_WINDOW_XID(window) : 0;
 }
 
-static void window_center(GtkWindow *window)
-{
-	GdkRectangle rect;
-	int x, y;
-	int screen;
-	
-	screen = gdk_screen_get_number(gtk_window_get_screen(window));
-
-#if GTK_CHECK_VERSION(3, 22, 0)
-	gdk_monitor_get_workarea(gdk_display_get_monitor(gdk_display_get_default(), screen), &rect);
-#else
-	gdk_screen_get_monitor_workarea(gdk_screen_get_default(), screen, &rect);
-#endif
-
-	x = rect.x + (rect.width - width()) / 2;
-	y = rect.y + (rect.height - height()) / 2;
-
-	gtk_window_move(window, x, y);
-}
-
 //-------------------------------------------------------------------------
 
 static bool desktop_has_system_tray()
@@ -134,7 +114,6 @@ void *GB_GTK3_X11_1[] EXPORT = {
   (void *)platform_create_plug,
 
   (void *)window_get_id,
-  (void *)window_center,
   
   (void *)desktop_has_system_tray,
   (void *)desktop_show_tray_icon,

gb.qt4/share/gb.form.arrangement.h

@@ -393,9 +393,15 @@ void FUNCTION_NAME(void *_object) //(QFrame *cont)
 						{
 							if (IS_EXPAND(ob)) // && !autoresize)
 							{
-								h = sexp / nexp;
+								if (nexp == 0) // the list of expanded widget may change
-								sexp -= h;
+									h = 0;
-								nexp--;
+								else
+								{
+									h = sexp / nexp;
+									sexp -= h;
+									nexp--;
+								}
+								
 								if (h <= 0)
 									MOVE_WIDGET(ob, wid, -GET_WIDGET_W(wid), GET_WIDGET_Y(wid));
 							}
@@ -426,9 +432,17 @@ void FUNCTION_NAME(void *_object) //(QFrame *cont)
 						{
 							if (IS_EXPAND(ob)) // && !autoresize)
 							{
-								w = sexp / nexp;
+								if (nexp == 0) // the list of expanded widget may change
-								sexp -= w;
+								{
-								nexp--;
+									w = 0;
+								}
+								else
+								{
+									w = sexp / nexp;
+									sexp -= w;
+									nexp--;
+								}
+								
 								if (w <= 0)
 									MOVE_WIDGET(ob, wid, GET_WIDGET_X(wid), -GET_WIDGET_H(wid));
 							}