+void Widget::set_visible(bool v)
+{
+ if(v==visible)
+ return;
+
+ visible=v;
+
+ if(!visible && parent)
+ parent->child_hidden(*this);
+}
+
+void Widget::set_focus()
+{
+ if(!parent)
+ throw InvalidState("No parent");
+ if(!visible)
+ throw InvalidState("Can't set focus on invisible widget");
+
+ parent->grab_focus(*this);
+}
+