No context menu when right-clicking on waypoint

[morevnaproject]

This is reproducible in current master branch (8bf9c30).

1. Download and open sample file -
   wp-right-click-bug.sifz.zip
2. Select group "1".
3. Try right-clickig on waypoints, which I indicated on screenshot below -
   

Notice that no menu shown after right-click.

For other waypoints menu show normally.

This seems to be related with #2858 fix.

@mohamedAdhamc can you take a look, please? ^__^

[mohamedAdhamc]

@morevnaproject sure, I will hopefully start looking into it tonight :).

update: seems that this issue happens when the canvas waypoint is only present due to it referring to another groups parameter, but when the canvas waypoint is referring to at least one layers parameter as well it works fine. I will reinvestigate the whole waypoint collection process tomorrow hopefully and I should reach the problem from there hopefully.

update 2: I have come up with a solution here, will clean it up a bit and then submit a PR hopefully tonight (in a few hours) :).