Modifying ComboBox SelectedIndex Without Triggering Event in C#

Question

My C# application has a comboBox with a SelectedIndexChanged event. Usually, I want this event to fire, but but sometimes I need the event to not fire. My comboBox is an MRU file list. If a file in the list is found to not exist, the item is removed from the comboBox, and the comboBox SelectedIndex is set to zero. However, setting the comboBox SelectedIndex to zero causes the SelectedIndexChanged event to fire, which in this case is problematic because it causes some UIF code to be run in the event handler. Is there a graceful way to disable/enable events for C# form controls? Thanks.

Answer 1

Start the eventhandler method with

ComboBox combo = sender as ComboBox;
if (combo.SelectedIndex == 0)
{
    return;
}

If you're issue is with a different eventhandler you could remove the eventhandler's event registration first.

combo.SelectedIndexChanged -= EventHandler<SelectedIndexChangedEventArgs> SomeEventHandler;
combo.SelectedIndex = 0;
combo.SelectedIndexChanged += EventHandler<SelectedIndexChangedEventArgs> SomeEventHandler;

Answer 2

One (fairly ugly) way would be to set a flag in the code that deletes the entry and then check that in the SelectedIndexChanged handler:

if (!deletedEntry)
{
    // Do stuff
}
deletedEntry = false;

A better way might be to remove your SelectedIndexChanged event handler at the start of the delete method and reinstate it at the end. This way you code won't know the index has changed.