Sets the background and outline colors of a dialog window.
If colors are not specified, default UI colors are used.
dlg_set_color(handle, background_color, outline_color)
Set custom colors for a dialog (background and outline)
dlg_set_color("dialog_123", 0xFF0000FF, 0xFFFF0000);
Use default UI colors
dlg_set_color("dialog_123", 0, 0);