Many dialogs/windows/splitters positions and/or sizes are persisted by saving them to configuration file. But if something bad happens, the user has to edit the configuration file manually to change or remove values.
An example of this situation is described in PICARD-592

Adding a command-line to force Picard to ignore those saved values would be useful to:

• users having UI issues on startup (too small, too big, out of screen, etc...)
• devs, for testing purposes