specify texture id in the sprite command

src/ugui_font.c3

@@ -210,4 +210,10 @@ fn Rect! Ctx.get_text_bounds(&ctx, String text)
 	}
 
 	return text_bounds;
+}
+
+// TODO: check if the font is present in the context
+fn Id Ctx.get_font_id(&ctx, String label)
+{
+	return (Id)label.hash();
 }