TPeriodItemEditor displays STARTTIME and ENDTIME and not MinTime and MaxTime. As it should be according to the instructions. What's wrong with me?
I'm sorry but I do not understand your remark.
A PlannerItem has a start time & end time, regardless of the type of the time-axis.
So, this editor allows you to set the PlannerItem start time and end time.
I kind of don't understand that. Here I only analyze what is part of your package Not what I can do on my own.
TPeriodItemEditor - by name I assume it will set the period boundaries! MaxTime and MinTime?
All three ItemEditors set the StartDate and EndDate
For this reason, TPeriodItemEditor is useless and functionally almost identical to TSimpleItemEditor! Lets you set a different day for EndDate. I don't know what it's for. Can you explain that to me?
Why do all TDBxxSource properties have MaxTimeField and EndTimeField? I did not find out their purpose.
I created derived components from TxxxItemEditor. By copying and renaming the original sources.
I added a ComboBox to all three TMyxxxItemEditor. In the AssignFromPlannerItem event, the ComboBox is always nil.
Prior to the last update, this error only applied to one of them. I'm not sure which one it was.
How do I prevent this from happening?
I quote:
- MaxTimeField/ MinTimeField: full date/time field that holds the last occurrence end date of an event. This is an optional field only used when recurrency capabilities are required in the application. See chapter on TDBPlanner recurrency.
The embedded samples from my program did not explain it to me. Note the date 7.1.2021. There is only one event. I think there should be two. Due to MaxTime and MinTime.
I apologize for the long post.
Part 2
I don't really know what the period is.
I have items in Subject1
a) The period is determined by StartTime (1/1/2021) and EndTime (3/1/2021). The lifetime of the event is 4 days. Regardless of recurrency.
b) The period is determined by MinTime (1/1/2021) and MaxTime (31/1/2021). StartTime (1/1/2021) and EndTime (1/1/2021). The lifetime of the event is 1 day. The recurrency has a shelf life of one month.
c) ???
Can you explain it to me? Don't get bogged down.
You have not created an input option for the MinTime and MaxTime properties.
Let's ask the question of repetition
I quote
(1) The recurrency support in TDBPlanner is transparent. Recurring planner items have the same DBKey, a public property TPlannerItem.Recurrent indicates whether an item is recurrent and the property TPlannerItem.Recurrency holds the recurrency formula. (2) The properties TPlannerItem.RecurrentStart: TDateTime and TPlannerItem.RecurrentEnd hold the start and end times of the first event in the recurrent series. When moving one of the items in a recurrent series, all items in the series move along the same delta time.
Part (1) is clear.
Part (2) TPlannerItem.RecurrentStart property: TDateTime - which value does it retrieve? Do I need to add fields to the DB?
The TPlannerItem.RecurrentEnd property is probably "Until date" - this probably needs to be added to the DB.
Or are they MinTime and MaxTime?
When moving one of the items in a recurrent series, all items in the series move along the same delta time.
I kind of don't understand this sentence.
The repetition is governed by TPlannerItem.Recurrency. If I understood correctly, it does not take MinTime and MaxTime into account. If I want to take them into account, I have to do it. Why? And how? Each item has different data. I can't do Query.SQL.Text.
I also take gradual answers 
It doesn't have to be all at once.
There is
TSimpleItemEditor
TPeriodItemEditor
DefaultItemEditor
There are all 3, item editors, i.e. dialogs allowing to edit properties of items.
An item has a start and end time, so that is what can be edited.
The concepts minimum / maximum time are properties of the TPlanner, NOT a TPlannerItem, hence these are NOT edited with a TPeriodItemEditor.
TPeriodItemEditor offers input of start date + time and end date + time because it is typically used when the items are put on a Planner with a multi day period time axis.
A TSimpleItemEditor offers input of start date + time and end time as this is suited to a Planner with an intra-day time axis and items are typically happening within a day.
I hope this clarifies what these editor components do.
The concepts minimum / maximum time are properties of the TPlanner, NOT a TPlannerItem,
I needed to know this. I didn't catch it anywhere. Well thank you.