C# DateTimePicker stuck in loop

Question

I have a datetimepicker in C#. When I click on it, it expands to show a monthly calendar, when I click the left arrow to go back a month, it changes the value and calls my even

Answer 1

The DateTimePicker ValueChanged event is buggy. Per Microsoft Windows Forms Team on this page https://connect.microsoft.com/VisualStudio/feedback/details/1290685/debugging-datetimepicker-event-hangs-vs:

"The DateTimePicker control installs a mouse hook as part of its functionality, but when the debugger has the WinForms application stopped on a breakpoint, it allows the possibility of a deadlock if VS happens to get a mouse message. For now, the deadlock is unfortunately a consequence of the DateTimePicker's design. The mouse hook is installed when the drop down is clicked to display the calendar. This means that breakpoints should not be sent in any event handlers which would be called while the calendar is active. We are currently investigating whether it is possible to address this issue and we will update this thread with further information if we are able to make a fix available."