color/colormap oddities

["Karl H. Beckers" <karl h beckers gmx net>]

Hello,

any pointers to a solution welcome, TIA ...

I have this app which has one GtkWindow and a number of small GtkDialogs
I'm abusing to mark an area on screen with an always-on-top rectangle.

These GtkDialogs are painted red in an expose-event event handler.

> //paint parts of frame on expose
> static gint on_expose_paint(GtkWidget *w, GdkEventExpose *e) {
>         GdkGC *gc;
>         GdkColormap *colormap;
>         GdkColor g_col;
>         int n;
>                                                                                                                              
>
>         gc = w->style->fg_gc[GTK_WIDGET_STATE (w)];
>         colormap = gtk_widget_get_colormap (w);
>         if (gdk_color_parse("red", &g_col)){
>                 if (gdk_colormap_alloc_color(colormap, &g_col, FALSE, 
> TRUE)) {
>                         gdk_gc_set_function ( gc, GDK_COPY );
>                         gdk_gc_set_fill ( gc, GDK_SOLID );
>                         gdk_gc_set_line_attributes ( gc, 3, 
> GDK_LINE_SOLID, GDK_CAP_BUTT, GDK_JOIN_MITER );
>                         gdk_gc_set_foreground ( gc, &g_col );
>                         gdk_draw_rectangle (w->window, gc, TRUE, 0, 0, 
> w->allocation.width, w->allocation.height);
>                  }
>         
> }                                                                                                                            
>
> }


If I do this, some widgets get painted red as well (even in other dialogs
opened from the main window), e.g. the downward arrow in a spinbutton
where you're already at the lowest value of the range.

Looks to me like I'm messing up my colormap ... but how and why (on
a TrueColor display).

Any pointers and RTFMs welcom,

Thanks,

Karl.