[Mono-winforms-list] VisualStyles implementation based on GTK+

[George Giolfan]

> > On Windows, in the
> HKEY_CURRENT_USER\Software\Mono registry key, you
> need to add a string value named "VisualStyles"
> with the data "GTK+".
> > On non-Windows platforms you can either use DLL
> mapping for the GTK+ libraries or disable the "#define
> Windows" line in GtkPlus.cs.
> 
> This is fine for your testing, but before we support this,
> we need to 
> default this to non-Windows platforms, and we probably
> won't support 
> running this on Windows.  (I can't think of a use-case
> for using GTK 
> native styles on Windows, other than testing.)

I see. I changed it so that on non-Windows platforms it will use GTK+ (if possible) without the need for any changes. On Windows I will define VISUAL_STYLES_USE_GTKPLUS_ON_WINDOWS when I want to test it.