Allow specifying only one of width and height in per-app settings size

[chaz/openbox] / themes / Natura / openbox-3 / desk_hover.xbm

#define desk_hover_width 8
#define desk_hover_height 8
static unsigned char desk_hover_bits[] = {
   0x00, 0x88, 0x88, 0xf8, 0xff, 0xf8, 0x88, 0x88 };