Some more ingo after investigation: it is not a matter of "between reboots", but of not writing out config about a dialog in the cache if the dialog was not used.
To reproduce:
Open ZIM, open DateDialog, change settings. Close ZIM
Open ZIM, open DateDialog: settings are remembered
Open ZIM and DO NOT open DateDialog, Close ZIM. Now settings for DateDialog are not written out!
Some more ingo after investigation: it is not a matter of "between reboots", but of not writing out config about a dialog in the cache if the dialog was not used.
To reproduce:
Open ZIM, open DateDialog, change settings. Close ZIM
Open ZIM, open DateDialog: settings are remembered
Open ZIM and DO NOT open DateDialog, Close ZIM. Now settings for DateDialog are not written out!
Open ZIM again: settings for DateDialog are lost.