[GREENFOOT-504] Allow multiple editor windows
In Java and Stride editors:
Add a right-click context menu for tab header, and same entries in the "Class" menu:
- "New window" (Disabled when this is the only tab in the current window)
- "----------" (Divider)
- "[Window title 1]" entries for each other open window of that kind (Java/Stride)
Should be available for web view tabs in Stride window, too.
Menu is easy enough, but we'll need to make sure we haven't made assumptions about there only being one SwingTabbedWindow/FXTabbedWindow per project.
- Issue type: Task
- Priority: Medium
- Fix versions: 3.0.2