Stunner - AbstractProjectDiagramEditor - Editor Lock icon reset when viewing different versions

AbstractProjectDiagramEditor updates the editor title when loading. The same process is followed when loading different versions of the file (from the Overview tab or from the Versions dropdown). If the file was locked (i.e. a User started editing the file) the editor title shows a "lock" icon (from an event fired from LockManagerImpl) however selecting a different version leads to the title being reset and the icon disappearing although it remains locked.

The Project Explorer continues to, correctly, show the "lock" icon.

This behaviour is different to all other editors that retain the "lock" icon when selecting different versions.

Arguably when a different version is selected the lock should be released anyway and it only reacquired when the User initiates editing again. Furthermore when a different version is selected the User should probably be prompted to save any changes before selecting a new version; or selection of a different version should be blocked if there are unsaved changes.

eignatow abakos@redhat.com What do you think, regarding the last sentence? Should the workbench block switching versions if there are unsaved changes; and should the lock be released when selecting a read-only version?

IDK how Spaces handle this.

PR Acceptance test

prerequisite: chrome, firefox, ie11

1. Create process
2. Save changes multiple times
3. Restore to some older version
4. Do some changes, check process is marked as dirty/locked
5. Repeat last two steps multiple times