ScenarioManager: Fix reload on property edit

When a property is changed the underlying file is saved which leads to the property window being reloaded (as of !100 (merged)). As a result of this reload, the property editor will scroll all the way to the top. This can be very annoying and distracting when changing properties while being scrolled down and may lead one doing accidental changes to other properties when the window suddenly changes.

We should ignore any file changes that we initiated ourselves which will fix this problem.