tdf#111782: fix Wrong rendering of image radiobutton on Split Cells dialog

The radio button icon was too big and there weren't enough space to render the
bottom border, so I reduced the size of the radio button icon.

Change-Id: Ie93f21ca730329716d0d209726e4d41c5d235b88
Reviewed-on: https://gerrit.libreoffice.org/45097Reviewed-by: Tamás Zolnai <tamas.zolnai@collabora.com>
Tested-by: Tamás Zolnai <tamas.zolnai@collabora.com>

vcl/source/control/button.cxx

@@ -1938,6 +1938,11 @@ void RadioButton::ImplDrawRadioButtonState(vcl::RenderContext& rRenderContext)
             aImageSize.Width()  = CalcZoom(aImageSize.Width());
             aImageSize.Height() = CalcZoom(aImageSize.Height());
 
+            aImageRect.Left()++;
+            aImageRect.Top()++;
+            aImageRect.Right()--;
+            aImageRect.Bottom()--;
+
             // display border and selection status
             aImageRect = aDecoView.DrawFrame(aImageRect, DrawFrameStyle::DoubleIn);
             if ((ImplGetButtonState() & DrawButtonFlags::Pressed) || !bEnabled)