When a native popup window is positioned relative to a placement target on
the root window and the root window is moved or resized, the popup position
should update to reflect the new position of the placement target.
If a native popup window is positioned relative to another popup, as in the
case of sub-menus, and the parent popup is moved due to a change in the
position of its placement target, the child popup should also update
relative to the new position of the parent popup.
- Adds a "resize reason" to platform `Resized` events
- Which is used by the auto-sizing code to determine whether to reset `SizeToContent`
- Also other improvements to the reset logic for `SizeToContent`:
- Don't reset it if the size hasn't changed
- Don't reset it if `CanResize == false`
- Only reset the dimensions whose size has changed
- Obsolete the `BeginAutoSizing`/`AutoSizing` feature in `WindowBase`
- Renamed `MaxClientSize` to `MaxAutoSizeHint`
- On Windows get its value from `WM_GETMINMAXINFO` message
- Remove `ILayoutRoot.MaxClientSize` as it's not used any more
Simon Haines
Dan Walmsley
Steven Kirk
Nathan Garside
Nikita Tsukanov