ref: 10efd2806c04f7e9e9773dc0a73dd295edc227cf
dir: /sys/src/libcontrol/group.h/
typedef struct Group Group;
struct Group {
Control;
int lastbut;
int border;
int mansize; /* size was set manually */
int separation;
int selected;
int lastkid;
CImage *bordercolor;
CImage *image;
int nkids;
Control **kids; /* mallocated */
Rectangle *separators; /* mallocated */
int nseparators;
};