Fine-grained control over external display window

[bluedarter]

I would like to have a mechanism for fine-grained control over the display window when the "Present on External Display" option is used.

My use model for Affinity Designer, on Windows VM and iPad, (I would LOVE to have a Linux-native version) is to modify/customize sewing patterns (imported PDF), then use Designer on iPad to project the pattern using an external projector (wi-fi or hdmi). I project the pattern down onto my fabric on a cutting surface.

I set "Present on External Display".  This way I can have a good overview of the pattern on my iPad, move around, zoom in and out,  make spot alterations, while *separately* controlling the part being projected onto the fabric and cutting surface.  Note that I *must* set the zoom level specifically for the projected pattern so that the projected measurements (pattern pieces) are sized correctly.

I usually can't project the whole pattern all at the same time.  I must shift the external display around to show the parts of the pattern I want to cut out.

The issue I have stems from the fact that, since sometimes I can't display the whole pattern piece at once, I need to shift the external display window AND the fabric in concert making sure that previously-cut fabric and displayed pattern piece are properly aligned.

As it stands, when using the "Present on External Display" setting, my only choice for moving the external display is by using the little window shown in the Navigation pop-out on my iPad screen.  The control available there is at a very gross level, and it is very difficult to control.