I am not sure that we are speaking about the same thing because I did not succeed in moving the toolbar through click and drag. I think your have speaking about the dockable “widgets” (Layers widget, Brush setting widget, History widget, Canvas Overview widget).
To have it on the right or left with larger icons (i.e., the user could chose the size) would help a lot while working on tablets: you could select the tool you want with your thumb of the left hand and use the tool with your right hand.
It would also allow to zoom and pan more easily (although a multi-gesture support would be even better).
No sadly the the top bar and the bottom bars are set in stone so to speak so that is not possible. If space is a problem, you could go into full screen mode and press TAB, it will go into auto hide the UI and give you the full canvas. Just either go to the top to see the reveal the tool bar or press TAB again to reveal the UI.
With HiDPI, it’s sounding more like an upstream issue with GDK or GTK since on Linux, HiDPI support is working. We can help you with reporting it upstream to see if there is an issue.
Lastly Mutitouch is a much needed feature request, so we’ll accept any pull requests if any code contributors wants to add the support to MyPaint.
With that said, I am going to move this the user support category since you are asking for more than one thing on MyPaint.
It is not a problem of space but a problem of being able to easily select the tools with the left/right hand while holding the tablet.
I am mainly concern in using MyPaint without keyboard in fact, in tablet mode, making MyPaint more travel friendly.
Ok, so I need to report the HiDPI issue to GDK/GTK.