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While qualifying most events synchronously is harmless, events such as OnGotFocus or OnLostFocus must be asynchronous. These events occur when the control has received focus, which prompts the control to perform a lot updates to its state, but OI also wants to do a lot of stuff when focus changes. If these events are synchronous, OI will sometimes will try to update the state of all the other controls on and the form while the ActiveX control was in the middle of updating it's own state. This leads to focus flicker and unwanted clicks.

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