rem: if (fwin->on_mousedown_titlebar) (*fwin->on_mousedown_titlebar)(titlebar, fwin->child, event);
add: if (fwin->on_mousedown_titlebar) { (*fwin->on_mousedown_titlebar)(titlebar, fwin->child, event); }
context: titlebarMouseDown(WObjDescriptor *desc, XEvent *event){    WFrameWindow *fwin = desc->parent;    WCoreWindow *titlebar = desc->self;        if (IsDoubleClick(fwin->core->screen_ptr, event)) {	if (fwin->on_dblclick_titlebar)	    (*fwin->on_dblclick_titlebar)(titlebar, fwin->child, event);    } else {	if (fwin->on_mousedown_titlebar)	    (*fwin->on_mousedown_titlebar)(titlebar, fwin->child, event);    }}