Only have active buttons for undo/redo if there is something to undo/redo

[claell]

Is your suggestion for improvement related to a problem? Please describe.
The current buttons for this can always be clicked. There is no visual clue or prevention from clicking them needlessly.

Describe the solution you'd like
Other applications deactivate them in cases where nothing can be undone/redone.

Additional context

[ThiloteE]

@calixtus

[calixtus]

Undo redo is currently partially broken and does not work consistently.
We have a very large project running in the background to modernize the codebase (up to 20 years old) and to implement certain design patterns like the command pattern. As soon as this is done fixing the undo manager should be a fairly simple task. But there is still some way to go...

[claell]

Alright! I guess, that also explains #8770.

[calixtus]

Sadly yes... 😅

[claell]

Corresponding relevant line for the future seems to be this:

jabref/src/main/java/org/jabref/gui/undo/UndoRedoAction.java

Line 33 in 6a2332f

this.executable.bind(ActionHelper.needsDatabase(stateManager));