Yes, i can use this event. But in this method there's not possibility to cancel it (see e.cancel = true) and force the user to change the value.

I have a problem with the validating event of the datimepicker-control. I use this event to check the correct value of the date i.e. the inputed date shouldn't be in the past. Normally it works fine, but if you manually change the date via keyboard and leaving the control pressing the TAB key, the property 'Value' of the datetimepickers holds the old value. But this only happens, if you i.e. change the month from '01' to '2'. Changing the month from '01' to '02' is working correctly. Any ideas why this is happening and how to resolve it?

thank you for your answer. i decided to use a usercontrol. There is one difficulty. The button must be inside the textbox and the entered text mustn't hidden by the button. How to combine controls, that the result looks like one textbox with described features.

Think about inputing a filename. You can enter the name directly or you can open another dialog to choose a filename. The button has the function to open another dialog depending of the context. The combobox has also the button inside. We want to use these controls with normal textboxes, comboboxes and others together on one form. The alignment, the look and feel must be same for all controls. (Also the big boss has decided it.)

Hello, I want to create a control like a textbox additionally with a button inside. So i created a new class with base class TextBox. I wrote code into the constructor to create dynamically the button and position ist right-aligned. This works fine but the problem is that longer text is hidden behind the button. Is there any solution for this. Using usercontrols is no solution because the new control should look as a textbox with all his properties and methods.