Minimum window size can now be customised and set at runtime via the
SetWindowMinimumSize WindowServer message and the set_minimum_size
LibGUI::Window method. The default minimum size remains at 50x50.
Some behind-the-scenes mechanics had to be added to LibGUI::Window to
ensure that the minimum size is remembered if set before the window is
shown. WindowServer sends a resize event to the client if it requests a
size on create that's smaller than it's minimum size.
The WM_* IPC messages are intended for "outsider" window management,
not for a client's own windows. Make a separate StartWindowResize
message for this.
This was the only reason that every IPC client had to know its server
side client ID.
Adds a mechanism through which windowing clients can re-request an
UpdateSystemTheme message. This is currently used in SystemMenu's
ShutdownDialog to refresh it's theme when the dialog is instantiated.
Instead of storing the back/front buffers of a GUI::Window as just
Gfx::Bitmap, wrap them in a WindowBackingStore class.
This will allow us to add more information alongside the bitmaps while
keeping the back/front swapping logic simple.
