- restore copy image functionality* in image context menu, current image buttons
- give IAIDndImage the same context menu
* copying image to clipboard is not possible on Firefox unless the user enables a setting which is disabled by default. if the browser does not support copying an image, the copy functionality is disabled.
Add `useMinimumPanelSize()` hook to provide minimum resizable panel sizes (in pixels).
The library we are using for the gallery panel uses percentages only. To provide a minimum size in pixels, we need to do some math to calculate the percentage of window size that corresponds to the desired min width in pixels.
