Picture-in-Picture: hard to resize without moving away from bottom/right edges

## Problem

Its hard to resize the Picture-in-Picture window, if it is placed in the lower right corner of the screen. That's due to the resize button beeing in the bottom right corner - therefore it is not possible to make the Picture-in-Picture window bigger without beeing moved away from the corner first.

## Proposal

When using Picture-in-Picture mode, the close and resize buttons should be placed depending of the position of the Picture-in-Picture window:

If the Picture-in-Picture window is:

- in the upper-left of the screen: close button is top-left, resize button bottom-right
- in the upper-right of the screen: close button is top-right, resize button is bottom-left
- in the lower-left of the screen: close button is lower-left, resize button is top-right
- in the lower-right of the screen: close button is lower-right, resize button is top-left

This way, the Picture-in-Picture window can easily placed in any corner - but keeps resizable without the need of previously moving the window to another place.

## Prior Art

Basic functionality is already there - I guess the only part missing is detecting screen position and adjusting button placement accordingly.