Why are my MonthCalendars not dropping down (C# / Windows Forms)?

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I copied-and-pasted all the controls on a form to another to ease the process of creating a new app based on the look and feel of the exiting one. Included in the copied controls were two MonthCalandars. Their AllowDrop and Enabled properties are true. They only contain one event, for the DateSelected event, and the code is identical:

C#

private void monthCalendarBegin_DateSelected(object sender, DateRangeEventArgs e)
{
    beginDateText.Text = monthCalendarBegin.SelectionStart.ToShortDateString();
    monthCalendarBegin.Visible = false;
}

However, in the original app, clicking monthCalendarBegin (and monthCalendarEnd) cause/allow the MonthCalendars to drop down; in the new app, they do not. There is no err msg, they simply don't drop.

I compared all the property settings, and they are identical; what could be causing this?

Posted 29-Oct-15 7:21am

B. Clay Shannon

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BillWoodruff 29-Oct-15 14:52pm

Very unlikely, but: is there any difference in: the versions of the controls you copy-paste and the same controls on the toolpalette in the version of Visual Studio you paste into ? difference in the Visual Studio versions being used; any difference in .NET FrameWork versions used here ? If you start a new WinForm Project, and copy-paste the two MonthCalendars into a Form, same behavior ?

I'd certainly want to inspect the Designer.cs code for the two Controls to see if anything "strange" shows up.

B. Clay Shannon 29-Oct-15 14:59pm

Yes, I checked both the *.cs and the *.designer.cs, with nothing different (even the name is the same). Both are VS 2013, and I copy-pasted the controls from one form to the other. The MonthCalendars *will* drop down when the associated TextBox is clicked (due to code that does that: monthCalendarBegin.Visible = true;), but there is no "click" event for the MonthCalendar controls themselves.

George Jonsson 29-Oct-15 18:50pm

I have had similar problems when copying controls, but the cause has always been that I have forgotten to attach the event in the design file as this is not done automatically.
Can you show the relevant code for the design of monthCalendarBegin?

B. Clay Shannon 29-Oct-15 19:00pm

Thanks, but the only event is DateSelected, and that has been added, too. It is very odd; the code seems just the same, yet the two projects behave differently in that respect.

George Jonsson 29-Oct-15 19:04pm

OK, then you indeed have a weird problem.
What if you add a new MonthCalendar as a test and see if that one drops down.

B. Clay Shannon 29-Oct-15 19:19pm

Maybe it's just that I don't know MonthCalendar controls; this is what I did: I dropped a new MonthCalendar on the form. I can see it there "dropped down" - just like the ones that were already there/copied over. And so when I run the app, there it is opened from the git-go (which is not what I want). To set them the same as the exisitng controls, I set AllowDrop to True and Visible to False; however, now I see nothing when I run the app (I can see the icons of the other/original ones; they are glyphs that represent a calendar. I'm wondering now that this is not the norm, and that some magic is going on to display the invisible calendars in this way...?

Aha! That *is* what it is - those glyphs are not the MonthCalendar in "hibernation" (scrolled-up) mode, as I assumed, but Buttons.

So that was it - my unfamiliarity with the MonthCalendar controls, coupled with the calendar-glyphed buttons being hidden behind the MonthCalendar controls at design-time, caused me to misinterpret the situation. Once I realized the buttons were indeed that, and copied over the corresponding Click event handlers for them, it now works - thanks for the nudge in the right direction!

George Jonsson 29-Oct-15 21:29pm

You are welcome. Sometimes it helps just to explain the problem to someone else and get a new point of view.

Philippe Mori 30-Oct-15 13:11pm

First of all, you should avoid copying forms if both are the same and reuse existing file instead...

UserControl combined with additionnal project is a good way to share common code too.

That being said, if you want to copy most of an existing form into a new one, it is often easier to copy the file and then remove what you don't need... Event handlers would stay connected as will localized resources, data source binding.

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