rem: XFreePixmap(pixmap->screen->display, pixmap->pixmap);
add: if (pixmap->pixmap) XFreePixmap(pixmap->screen->display, pixmap->pixmap);
context: WMReleasePixmap(WMPixmap *pixmap){    wassertr(pixmap!=NULL);    pixmap->refCount--;    if (pixmap->refCount<1) {	XFreePixmap(pixmap->screen->display, pixmap->pixmap);	if (pixmap->mask)	    XFreePixmap(pixmap->screen->display, pixmap->mask);	free(pixmap);    }}