Theme switching

["Miroslav Rajcic" <rajcic sokrates hr>]

I am trying to write a code to set a custom GTK theme for my program (should 
affect only my application).

The problem is that this sample code works fine on Windows, but not on 
Linux:

char *pszStyle = "gtk-theme-name = \"HighContrastInverse\"\nstyle \"custom\" 
{\nfont_name="Sans 10"\n} widget_class \"*\" style \"custom\"\n";
gtk_rc_parse_string(pszStyle);

Note that the theme exists on the test distro.

Is this officially supported ? Any tips ?
Should it work even after the application window was created ?