tdf#115895 - Color picker images missing in Impress

VirtualDevice does not have an alpha channel by default.

Change-Id: I4eebd7a23546a77dc9df2e2dad12d37eec4560ef
Reviewed-on: https://gerrit.libreoffice.org/50248Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Tomaž Vajngerl <quikee@gmail.com>

svx/source/tbxctrls/tbxcolorupdate.cxx

@@ -22,6 +22,7 @@
 #include <svx/svxids.hrc>
 #include <svx/xdef.hxx>
 
+#include <vcl/svapp.hxx>
 #include <vcl/toolbox.hxx>
 #include <vcl/virdev.hxx>
 #include <vcl/settings.hxx>
@@ -85,7 +86,8 @@ namespace svx
         if (!aItemSize.Width() || !aItemSize.Height())
             return;
 
-        ScopedVclPtr<VirtualDevice> pVirDev(VclPtr<VirtualDevice>::Create());
+        ScopedVclPtr<VirtualDevice> pVirDev(VclPtr<VirtualDevice>::Create(*Application::GetDefaultDevice(),
+            DeviceFormat::DEFAULT, DeviceFormat::DEFAULT));
         pVirDev->SetOutputSizePixel(aItemSize);
         maBmpSize = aItemSize;