Have you tried setting the ActivationGestures? If you need moire explanation with examples, you can go to our online documentation here for more details. As stated in the docs, "Activation gestures are key and/or text input, which cause an element to enter edit mode and are defined through a cell editor's ActivationGestures property (see Examples 1 and 2)". The F2 key should be reserved for editing. You can take a look at the EditModes sample application that was installed on your machine when you installed the component.
C:\Xceed Samples\Xceed DataGrid for WPF Professional Edition v4.3\CSharp\EditModes
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