@sgareau Hi this is a known issue that has already been reported and the developers are working on fully patching this problem. You can test any development version after October 7th to see the fix.
Please mind the timestamps found in the name of the file.
They look like: pencil2d-OS-year-month-date.zip
Win64 October 7th (Latest is from december 14th, but be careful as there are other issues we’re dealing with) https://drive.google.com/file/d/1aClxCCCyRqtKxkvQCkGiVRQN349Nh0TM/view?usp=sharing
Windows 64 bits dev build folder
Windows 32 bits dev build folder
macOSX dev build folder
Linux dev build folder
If you can’t or don’t want to download and test the dev builds you would have to wait for the developers to ship the improved interface in the next release, however right now you can perform certain workarounds as seen here Timeline keeps disappearing whenever I press ALT and here: Timeline keeps disappearing whenever I press ALT
The problem occurs basically because Pencil2D can’t find enough space to calculate the panels. This calculation is affected by screen resolution among other factors and the initial patch tries to make all panels scrollable. Further improvements will hope to sever the problem from root which occurs when Pencil2D loads its interface.