The Ubuntu Studio team would like to congratulate GIMP on the release of version 2.10! It has been years since the last major release of GIMP, and this one is a good one.
Unfortunately for our users that use MyPaint and GIMP, MyPaint (1.2) uses libmypaint 1.2. GIMP 2.10 uses libmypaint 1.3. The two libmypaint versions cannot currently be installed at the same time. This means that, until we devise a solution or MyPaint 1.3 is released (whichever comes first) MyPaint and GIMP 2.10 cannot be installed at the same time. This discrepancy is causing problems in the official Ubuntu repositories and in upstream Debian Testing.
The bug reports are as follows:
Rest assured, we are working on a solution. If you need to have both MyPaint and GIMP 2.10 installed simultaneously, until a solution is released, we recommend watching this page for a SNAP version of GIMP 2.10. Please note that at this time there is no upgrade path from a .deb package (such as GIMP included with Ubuntu Studio) to a SNAP package, so you may wish to uninstall GIMP 2.8, though with the SNAP both can be installed simultaneously.
Once we have a solution, it will land in the development version of Ubuntu Studio 18.10, and we hope to do an “exceptional” Stable Release Update for Ubuntu Studio 18.04.
We do apologize for this inconvenience, and we hope to get it straightened-out as soon as possible.