LibGUI+WindowServer: Start fleshing out drag&drop functionality

This patch enables basic drag&drop between applications.
You initiate a drag by creating a GDragOperation object and calling
exec() on it. This creates a nested event loop in the calling program
that only returns once the drag operation has ended.

On the receiving side, you get a call to GWidget::drop_event() with
a GDropEvent containing information about the dropped data.

The only data passed right now is a piece of text that's also used
to visually indicate that a drag is happening (by showing the text in
a little box that follows the mouse cursor around.)

There are things to fix here, but we're off to a nice start. :^)

1 files changed, 1 insertions, 0 deletions

diff --git a/Servers/WindowServer/WSClientConnection.h b/Servers/WindowServer/WSClientConnection.h
index b7d3bc4987..707c882d2f 100644
--- a/Servers/WindowServer/WSClientConnection.h
+++ b/Servers/WindowServer/WSClientConnection.h
@@ -92,6 +92,7 @@ private:
     virtual OwnPtr<WindowServer::DestroyMenuAppletResponse> handle(const WindowServer::DestroyMenuApplet&) override;
     virtual OwnPtr<WindowServer::SetMenuAppletBackingStoreResponse> handle(const WindowServer::SetMenuAppletBackingStore&) override;
     virtual OwnPtr<WindowServer::InvalidateMenuAppletRectResponse> handle(const WindowServer::InvalidateMenuAppletRect&) override;
+    virtual OwnPtr<WindowServer::StartDragResponse> handle(const WindowServer::StartDrag&) override;
 
     HashMap<i32, NonnullOwnPtr<WSMenuApplet>> m_menu_applets;
     HashMap<int, NonnullRefPtr<WSWindow>> m_windows;