I've actually tried all of the events including the suggestions here and none of the mentioned events occur at the right time to actually trap moving from the tab. NET 4 there is the Deselecting event which fires at the right time for my purposes.Even the tab page validation event fires when entering the tab rather than leaving it - either that or there's something peculiar going on with my machine or .

tabcontrol validating-64

Ideally, I think the best solution is not to leave a tab until the validating event has completed successfully. Being able to do that might help for my particular circumstances. If you have multi-tab entry form final validation should occur only when final tab page is filled and confirmed. I guess maybe I should have asked only how to prevent a user from leaving a tab page. I think you should hook the Validating event for all the controls on your form.

The problem I am experiencing is when a control fails its validating event and the user clicks another tab things get messy. I guess maybe I should have asked only how to prevent a user from leaving a tab page. You can combine this with Validating event, where you can set Cancel=true to prevent further events after Validating. Generally speaking, I would suggest to reconsider whole validation scheme you use now - whatever unusual things you are trying to do. Ideally, I think the Hi Dennis, Based on my understanding, you want to validating all the controls on the tabpage before switch pages.

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This example requires that a Text Box and Error Provider control have been created on a form.

the selected index actually changes, for validation purposes.

What happens is if I do in validating event of tabpage1, in the above case, when user clicks on tabpage1 by mistake having tabpage1 already selected, it will prompt user that "Do you want to stay on current tab to save data or move from the current tab? You could use the Selecting/Selected events and write some more logic yourself.

Or give up on either tabpages or the idea that they are to be validated individually.

Doing so can cause your application or the operating system to stop responding.

For more information, see the WM_KILLFOCUS topic in the "Keyboard Input Reference" section, and the "Message Deadlocks" section of the "About Messages and Message Queues" topic in the MSDN library at

Hello Thomas, When you give the Tab Control a Content Template and bind it to some collection of items, then switching between tabs makes the Tab Control unload the content of the last active item and load the content of the newly selected item.