LibGUI: Implement nested event loops to support dialog boxes.

This patch adds a simple GMessageBox that can run in a nested event loop.
Here's how you use it:

    GMessageBox box("Message text here", "Message window title");
    int result = box.exec();

The next step is to make the WindowServer respect the modality flag of
these windows and prevent interaction with other windows in the same
process until the modal window has been closed.

1 files changed, 1 insertions, 1 deletions

diff --git a/Applications/About/main.cpp b/Applications/About/main.cpp
index b98b4ca496..045b02681d 100644
--- a/Applications/About/main.cpp
+++ b/Applications/About/main.cpp
@@ -14,7 +14,7 @@ int main(int argc, char** argv)
     Rect window_rect { 0, 0, 240, 120 };
     window_rect.center_within({ 0, 0, 1024, 768 });
     window->set_rect(window_rect);
-    window->set_should_exit_app_on_close(true);
+    window->set_should_exit_event_loop_on_close(true);
 
     auto* widget = new GWidget;
     window->set_main_widget(widget);