diff --git a/lcl/interfaces/gtk2/gtk2int.pas b/lcl/interfaces/gtk2/gtk2int.pas
index b0f3517e4d..684a06db28 100644
--- a/lcl/interfaces/gtk2/gtk2int.pas
+++ b/lcl/interfaces/gtk2/gtk2int.pas
@@ -79,9 +79,11 @@ type
     FLastFocusOut: PGtkWidget;
     StayOnTopList: TMap;
     FAppActive: Boolean;
+    FCachedTitleBarHeight: Integer;
+    FCachedBorderSize: Integer;
     function GetAppActive: Boolean;
+    function GetTitleBarHeight: Integer;
     procedure SetAppActive(const AValue: Boolean);
-
   protected
     procedure AppendText(Sender: TObject; Str: PChar);
     function GetText(Sender: TComponent; var Text: String): Boolean;
diff --git a/lcl/interfaces/gtk2/gtk2widgetset.inc b/lcl/interfaces/gtk2/gtk2widgetset.inc
index 3feb55ced7..364743a34c 100644
--- a/lcl/interfaces/gtk2/gtk2widgetset.inc
+++ b/lcl/interfaces/gtk2/gtk2widgetset.inc
@@ -1088,6 +1088,8 @@ end;
 constructor TGtk2WidgetSet.Create;
 begin
   inherited Create;
+  FCachedTitleBarHeight := -1;
+  FCachedBorderSize := 4;
   Gtk2Create;
   {$IFNDEF USE_GTK_MAIN_OLD_ITERATION}
   FMainPoll := nil;
@@ -2622,6 +2624,42 @@ begin
   Result := FAppActive;
 end;
 
+function TGtk2WidgetSet.GetTitleBarHeight: Integer;
+var
+  I: Integer;
+  AForm: TCustomForm;
+  AWindow: PGdkWindow;
+  ARect: TGdkRectangle;
+  AW, AH: GInt;
+begin
+  Result := 30;
+  if FCachedTitleBarHeight > 0 then
+    Result := FCachedTitleBarHeight
+  else
+  if Assigned(Application) and not Application.Terminated and
+    Assigned(Application.MainForm) then
+  begin
+    for i := 0 to Screen.CustomFormZOrderCount - 1 do
+    begin
+      AForm := Screen.CustomFormsZOrdered[i];
+      if (AForm.HandleAllocated) and (AForm.Visible) and (AForm.Parent = nil) and
+        (AForm.BorderStyle <> bsNone) then
+      begin
+        AWindow := PGtkWidget(AForm.Handle)^.window;
+        if GDK_IS_WINDOW(AWindow) then
+        begin
+          gdk_window_get_frame_extents(AWindow, @ARect);
+          gdk_window_get_size(AWindow, @AW, @AH);
+          FCachedTitleBarHeight := ARect.Height - AH - 1;
+          FCachedBorderSize := (ARect.Width - AW) div 2;
+          Result := ARect.Height - AH - 1;
+          break;
+        end;
+      end;
+    end;
+  end;
+end;
+
 procedure TGtk2WidgetSet.SetAppActive(const AValue: Boolean);
 begin
   if AValue <> FAppActive then
diff --git a/lcl/interfaces/gtk2/gtk2winapi.inc b/lcl/interfaces/gtk2/gtk2winapi.inc
index e4bd20e345..7b5eb0367d 100644
--- a/lcl/interfaces/gtk2/gtk2winapi.inc
+++ b/lcl/interfaces/gtk2/gtk2winapi.inc
@@ -5542,7 +5542,7 @@ begin
     SM_CXSIZEFRAME,
     SM_CYSIZEFRAME:
       begin
-        Result := 4;
+        Result := FCachedBorderSize;
       end;
     SM_CXSMICON,
     SM_CYSMICON:
@@ -5570,6 +5570,7 @@ begin
     SM_CYCAPTION:
       begin
         //DebugLn('Trace:TODO: [TGtk2WidgetSet.GetSystemMetrics] --> SM_CYCAPTION        ');
+        Result := GetTitleBarHeight;
       end;
     SM_CYKANJIWINDOW:
       begin