Setting a folder colour in a toplevel folder is possible in the folder properties dialog interface, but the colour is not set on folder list.
Steps to reproduce:
• Right-click a toplevel folder (MH, IMAP, RSSyl) to open contextual menu
• Select “Properties...” option, dialogue opens
• Click “Folder color” squared colour spot, colour selector dialogue opens
• Select a non-black colour
• Close the colour selector clicking “OK” button, colour spot is updated
• Click “Apply” button
• Click “OK” button to close dialog
Right-clicked folder remains black instead of the selected colour.
If it's not possible the interface should be disabled (until the recursive checkbox is checked) or a warning raised, notifiying the invalid setting.
Preferred fix is that this could be possible, of course, as this can help to visually locate toplevel folders easily on folder lists.
This would require moving folder_color from FolderItemPrefs to Folder and FolderItem structs, and therefore storing it in folderlist.xml instead of folderitemrc. Thanks for volunteering! :)
As Chris Hirst pointed out on mailing list I completely overlook the label on the dialogue which says the preferences won't be saved.
Changing it to a feature request ;-)