Uniquely among apps, Stager (possibly other Substance 3D apps, I haven't checked) completely fails to implement the standard Windows kbsc UI components.
[Alt]+[letter] is a convention that opens a top-level menu in virtually every PC app; it even predates Windows. [Alt+F] usually opens the File menu, [Alt+E] the Edit menu, etc. Pressing [Alt] on its own shows underscores on the key character of each top-level menu item (File, Edit, etc.) so that pressing that character opens the associated menu. This applies also to items within menus. [Alt F A] as a key sequence activates "Save As" in a CC or Office app, to take one example. In InDesign, the sequence [Alt T E T] executes Type > Change Case > Title Case. There are dozens of such short sequences built into the muscle memory of any experienced Windows user.
Professional users of an OS rely on standard OS-wide UX to speed workflows and any app should conform to the standards of the platform it is running on. This particular UX is so much part of the base Windows spec that Stager and Dimension are the only Windows apps I have used in more than 25 years that don't implement it.
This a very basic feature request. Implementing it correctly may incidentally solve another uniquely Stager/Dimension bug whereby the UI becomes "detached" from the app, so that menus and frame buttons behave normally in themselves but no longer actually do anything. Anyone using either of these apps has run into the situation where the app appears to be running but menu selections have no effect. The only solution is to kill the app via Task Manager or Force Quit, with occasionally disastrous consequences for file integrity.
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