ref: b9f2b8c6a28c2d4744119c7254767a0f1b51ed2e
dir: /libwidget/button.h/
typedef struct Button Button; struct Button { Widget; Widget *content; int pressed; }; int isbutton(Widget*); Button* newbutton(Widget*); Button* newtextbutton(Font*, char *content); enum { M_BUTTON_PRESSED = C2I('b', 't', 'n', 'p') };