Try to follow the actual padding that FLTK adds to these widgets.
The extra one pixel on each is because of a bug in FLTK's focus drawing
code, where the box is always one pixel too small in both dimensions.
#define BUTTON_WIDTH 115
#define BUTTON_HEIGHT 27
-/* Fl_Round_Button */
-#define RADIO_MIN_WIDTH (FL_NORMAL_SIZE + 5)
-#define RADIO_HEIGHT (FL_NORMAL_SIZE + 7)
+/* Fl_Round_Button (padding + focus draw bug) */
+#define RADIO_MIN_WIDTH (FL_NORMAL_SIZE + 4 + 1)
+#define RADIO_HEIGHT (FL_NORMAL_SIZE + 4 + 1)
/* Fl_Check_Button */
#define CHECK_MIN_WIDTH RADIO_MIN_WIDTH