USING REMOTE CONTROL...and MASKING CONTROLS
If I choose BLU-RAY from the WATCH MOVIE page, it switches the source to Blu-Ray and ends on this page:

I like the fact all the transport and menu buttons are mapped to the remotes hard buttons for ease of use in the dark, freeing up the touch screen to have various options readily available. Pressing SOUND, or PICTURE brings me to pages allowing fine control.
You can see on the bottom right that there is a SCREEN SIZE button, like on the main home page. Pressing that button brings up pages from which I can select and manipulate image sizes. PAGE ONE:

PAGE TWO

What happens is I choose a pre-set Aspect Ratio/Image size button, say...16:9 115"
That starts the screen size changing and calls up the projector's lens zoom feature on the screen. As the masking is changing size I'm zooming the image out to fit the width of the screen - the projector is centered so it zooms out evenly on both sides. This makes it really quick and easy to just zoom until the edges of the image meet the new image width.
Then it's just a quick vertical shift up or down to adjust the image into place (the top/bottom masks will have stopped in place by that point).
This process is quick and painless. I have it down to as low as 12 seconds to change from one AR/image size to a new one. And guests tend to think it's way cool watching the process. I use the JVC RS20 projector's lens pattern, which has all the relevant ARs marked in "laser green" against a black background, and it really does look cool using it.