Resolves: tdf#73211 gtk checkboxes need erase afer toggling

because an unchecked checkbox can have a smaller paint area
than a checked checkbox. This has always bugged me

Change-Id: Iac0f075089611b47c381863a9655445d732bfddc

vcl/unx/gtk/gdi/salnativewidgets-gtk.cxx

@@ -538,6 +538,8 @@ void GtkData::initNWF()
     pSVData->maNWFData.mnMenuFormatBorderX = xthickness + horizontal_padding;
     pSVData->maNWFData.mnMenuFormatBorderY = ythickness + vertical_padding;
 
+    pSVData->maNWFData.mbCheckBoxNeedsErase = true;
+
     if( SalGetDesktopEnvironment() == "KDE" )
     {
         // #i97196# ensure a widget exists and the style engine was loaded

vcl/unx/gtk3/gdi/gtk3salnativewidgets-gtk.cxx

@@ -1472,7 +1472,11 @@ void GtkSalGraphics::WidgetQueueDraw() const
 static GtkWidget* gCacheWindow;
 static GtkWidget* gDumbContainer;
 
-void GtkData::initNWF() {}
+void GtkData::initNWF()
+{
+    ImplSVData* pSVData = ImplGetSVData();
+    pSVData->maNWFData.mbCheckBoxNeedsErase = true;
+}
 
 void GtkData::deInitNWF()
 {