I just checked with Xojo 2018r2;
the use of the arrow keys is working (to move in the Control list) / non working (navigate in the Events a-of a Control)
This also happens to me everyday, but now
I add 60 Properties in a Module and skipped an index letter (used to prefix the Properties).
So, to “renumber” the other Properties, I had to:
Move the Mouse to the leftmost part of the screen to select the Proprerty to make changes,
Move the Mouse to the top-rightmost part of the screen to make changes.
Boring and time consuming process. A better UI will not ask its user to do that.
Do not smile, when you are reviewing your code, you may have to do the same: click in the Navigator pane to select an entry to review.
Example: you review a Listbox code ('cause something wrong happens there): you have to use the Mouse to change the event when a single Top or Bottom arrow keypress can be enough (and some gesture on the TouchPad.
What ? Now you have your own examples on where you want to get that feature ? 
Express yourself !