It's not a bad idea actually. As I see it, there are two different ways of doing this from a user perspective:
1. IDE figures out what layout to open by looking for the LoadLayout command on the cursor line and then using the value therein
2. If there is selected text in the IDE, and that selection matches a layout name, that's the layout to be opened
In both cases the layout editor could be opened with a shortcut that lives in the Designer menu. Very non-obtrusive for those eager to use the files tab, and still quite helpful if you have a big project with lots of files and layouts.
I'd say I would prefer solution 2, as it would be more generic and easily allow me to open all three layouts from this example:
' All layouts part of the registration:
' registrationLayout, superSuccessfulLayout, epicFailLayout