SUMMARY When adding folders to a unified mailbox, there is no checkbox shown next to an account that comprises a single mbox file. This prevents the user from adding such a file to a unified mailbox. STEPS TO REPRODUCE 1. Create an account from an mbox file by going to Settings > Accounts > Receiving > Add account > Custom account > mbox, and selecting an mbox file. 2. In Settings > Plugins > Unified mailboxes > configure, click the 'edit' button for any existing unified mailbox 3. Try to select the mbox account to add it to the unified mailbox OBSERVED RESULTS The mbox account has no checkbox next to it to add it to the unified mailbox. This is because it appears as a top-level item without any subfolders. EXPECTED RESULTS If a top-level item (in this case, the mbox account) does not have any subfolders, a checkbox should be shown on it to add it to the unified mailbox. SOFTWARE VERSIONS Operating System: Arch Linux KDE Plasma Version: 5.25.5 KDE Frameworks Version: 5.97.0 Qt Version: 5.15.6 Kernel Version: 5.15.67-1-lts (64-bit) Graphics Platform: X11