Wrong default window size - Linux - Xojo2016

I have an app (a game), started in RS2012, updated to Xojo2015r4.1 and the app works well.
I need the return key to perform a specific action, so I made a button and made it default. It’s action event runs the required code. The button is positioned off the window, so it will not be visible. The window is not resizeable. This works.

When run in the 2016r1 debugger or in an app compiled by 2016, The window opens to the wrong size. Not only does it open too wide (to include the off screen button) but also the height is too short. It shortens up to touch the bottom of the lowermost control.

The workaround is to change the size in the window open event, but, is this something that should be fixed, or was it done on purpose for some reason?

It is reproducible in a simple new app. It does not happen if the offscreen button is not the default.

Don Jungk
Linux Mint 17.3 Mate 32 bit