Steps to reproduce:

1. Group an Explorer Window and another program together.

2. Open a separate Explorer Window, don't group it, but resize it.

3. Minimize the group using the Explorer Window from step 1.

4. Restore the group from the Taskbar by clicking on the other program from step 1.

5. Click on the Explorer Window tab in the group. When it switches tabs, the Explorer window will 'restore down' to the size of the un-grouped Explorer window from step 2.

Groupy 1.19

Windows 10 1809