Disappearing Toolbar Items

[a-sr]

In the Eclipse 2020-09 release the toolbar of the diagram view loses all its items as soon as an editor is switched. This commit fixes this issue.
However, the responsible code has the comment "important for correct toolbar layout". I guess I added it for a reason but I could not reproduce the problem that requires this line of code. Hence, in 2020-09 this line breaks the toolbar, in 2020-06 and 2020-03 this line makes no difference (tested) and probably in some previous release it was necessary.

I would say we want to have this bugfix anyway but you might want to check that it has no consequences for earlier releases that are important to you.

[a-sr]

@sailingKieler Christian, do you have an idea why updateActionBars() might have been necessary at one time.

[sailingKieler]

@sailingKieler Christian, do you have an idea why updateActionBars() might have been necessary at one time.

Could be that you copied this part from other implementation. I vaguely remember this call from the past, too.
Could be that one had to execute that in case menu contributions had to added (too) late wrt. expected time of the runtime.

Could also make a difference whether you added contributions via extension points, which is actually possible (a colleague of mine one day figured out how).

[NiklasRentzCAU]

I don't work on much earlier releases of Eclipse either and see no problem with this fix, If it allows us to support current releases of Eclipse as well.

[a-sr]

Ok, well it is code that changes the content of the toolbar and menu at runtime based on the model type but it obliviously works without this line now. Furthermore, such behavior will not work well with contributions added via extension points, which is not done anyway at the moment.
Hence, I would say we can merge it to fix this issue.

[NiklasRentzCAU]

Works in current versions and there are no objections, so LGTM