diff --git a/lcl/include/wincontrol.inc b/lcl/include/wincontrol.inc
index c54540f642..04ea9f61e9 100644
--- a/lcl/include/wincontrol.inc
+++ b/lcl/include/wincontrol.inc
@@ -7988,7 +7988,7 @@ procedure TWinControl.CalculatePreferredSize(var PreferredWidth,
     if not aControl.IsVisible then exit;
     if aControl<>Self then begin
       aControl.GetPreferredSize(w,h,true,true);
-      debugln([Prefix,'W ',DbgSName(aControl),' ',dbgs(aControl.BoundsRect),' Pref=',w,'x',h]);
+      debugln([Prefix,'Child ',DbgSName(aControl),' ',dbgs(aControl.BoundsRect),' Pref=',w,'x',h]);
     end;
     if aControl is TWinControl then
       for i:=0 to TWinControl(aControl).ControlCount-1 do
@@ -7997,7 +7997,7 @@ procedure TWinControl.CalculatePreferredSize(var PreferredWidth,
 
   function IsVerbose: boolean;
   begin
-    Result:=(Name='Edit1');
+    Result:=(Name='GroupBox1');
   end;
   {$ENDIF}
 
diff --git a/lcl/interfaces/gtk2/gtk2proc.inc b/lcl/interfaces/gtk2/gtk2proc.inc
index ebeb5d3393..e61ae05a01 100644
--- a/lcl/interfaces/gtk2/gtk2proc.inc
+++ b/lcl/interfaces/gtk2/gtk2proc.inc
@@ -6408,8 +6408,10 @@ var
   FixedWidget: PGtkWidget;
 begin
   Widget := {%H-}PGtkWidget(AWinControl.Handle);
-  //if AWinControl.Name='OtherInfoGroupBox' then
-  //  DebugLn(['GetGTKDefaultWidgetSize ',GetWidgetDebugReport(Widget)]);
+  {$IFDEF VerboseCalculatePreferredSize}
+  if AWinControl.Name='GroupBox1' then
+    DebugLn(['GetGTKDefaultWidgetSize ',GetWidgetDebugReport(Widget)]);
+  {$ENDIF}
 
   // set size to default
   gtk_widget_set_size_request(Widget, -1, -1);
@@ -6418,21 +6420,25 @@ begin
   PreferredWidth:=Requisition.width;
   PreferredHeight:=Requisition.height;
 
-  {if AWinControl.Name='OtherInfoGroupBox' then
+  {$IFDEF VerboseCalculatePreferredSize}
+  if AWinControl.Name='GroupBox1' then
     DebugLn(['GetGTKDefaultWidgetSize Allocation=',Widget^.allocation.x,',',Widget^.allocation.y,',',Widget^.allocation.width,',',Widget^.allocation.height,
      ' requisition=',Widget^.requisition.width,',',Widget^.requisition.height,
      ' PreferredWidth=',PreferredWidth,' PreferredHeight=',PreferredHeight,
-     ' WithThemeSpace=',WithThemeSpace]); }
+     ' WithThemeSpace=',WithThemeSpace]);
+  {$ENDIF}
 
   if GtkWidgetIsA(Widget,GTK_TYPE_EVENT_BOX)
   and (AWinControl.ControlCount>0) then begin
     // ignore client area (child controls)
     FixedWidget:=PGtkWidget(GetFixedWidget(Widget));
     if FixedWidget<>nil then begin
-      {if AWinControl.Name='OtherInfoGroupBox' then
+      {$IFDEF VerboseCalculatePreferredSize}
+      if AWinControl.Name='GroupBox1' then
         debugln(['GetGTKDefaultWidgetSize Fixed ',
          ' allocation=',FixedWidget^.allocation.x,',',FixedWidget^.allocation.y,',',FixedWidget^.allocation.width,',',FixedWidget^.allocation.height,
-         ' requisition=',FixedWidget^.requisition.width,',',FixedWidget^.requisition.height]);}
+         ' requisition=',FixedWidget^.requisition.width,',',FixedWidget^.requisition.height]);
+      {$ENDIF}
       dec(PreferredWidth,Max(0,FixedWidget^.requisition.width));
       dec(PreferredHeight,Max(0,FixedWidget^.requisition.height));
     end;
@@ -6440,8 +6446,10 @@ begin
 
   // restore size
   gtk_widget_set_size_request(Widget, AWinControl.Width, AWinControl.Height);
-  //if AWinControl.Name='OtherInfoGroupBox' then
-  //  debugln('GetGTKDefaultSize PreferredWidth=',dbgs(PreferredWidth),' PreferredHeight=',dbgs(PreferredHeight));
+  {$IFDEF VerboseCalculatePreferredSize}
+  if AWinControl.Name='GroupBox1' then
+    debugln('GetGTKDefaultSize PreferredWidth=',dbgs(PreferredWidth),' PreferredHeight=',dbgs(PreferredHeight));
+  {$ENDIF}
 end;
 
 procedure SendSizeNotificationToLCL(aWidget: PGtkWidget);
diff --git a/lcl/interfaces/gtk2/gtk2wsstdctrls.pp b/lcl/interfaces/gtk2/gtk2wsstdctrls.pp
index 64443ef881..871da87613 100644
--- a/lcl/interfaces/gtk2/gtk2wsstdctrls.pp
+++ b/lcl/interfaces/gtk2/gtk2wsstdctrls.pp
@@ -2377,6 +2377,7 @@ class procedure TGtk2WSCustomGroupBox.GetPreferredSize(
   const AWinControl: TWinControl; var PreferredWidth, PreferredHeight: integer;
   WithThemeSpace: Boolean);
 begin
+  // ToDo: compute the minimum size ignoring LCL child controls
   GetGTKDefaultWidgetSize(AWinControl, PreferredWidth, PreferredHeight,
                           WithThemeSpace);
 end;