| There are 2 ways.
1. right click it in Project Explorer and choose Restore.
2. Minimized windows actually are at bottom of workspace. U can click the 1st button (Restore) in the title bar to restore it.
3. For maximized window, the minimize/restore/x buttons are on the 2nd level upper-right corner of the whole workspace. (Note: not the Minimize/Restore/X button of the whole Origin workspace).
U can click Restore button to restore the child window.