I recently upgraded from picard 2.1.2 (what's in Debian stable) to the latest version, and after doing so I've noticed a couple new problems that have been introduced between those versions.
In the left hand pane (file selector), when you are navigating deeper into the tree, the pane keeps jumping around horizontally to keep the currently selected file or directory aligned at the same point even when at a different tree level. I can understand wanting to adjust the horizontal position if the entire file/directory name isn't visible within the pane, but it makes no sense and is really annoying if the entire name is already visible. That's the first bug.
The second bug is when clicking an arrow to expand/collapse a folder that is on a different tree level than whatever was last selected, the expand/collapse isn't performed, instead the display just jumps horizontally to re-center, and you have to move the mouse and click again to get the desired action.