Hi Antoine,
I'm not sure that's done easily because the property value editor can be anything. In some cases it might be a TextBox, in others an Editors edit box, or something completely different. It's up to the individual controls used in the property value editor template to determine how they react to mouse clicks.
You might be able to look at some PreviewMouseLeftButtonDown events or something like that on to try and catch a double-click before a child control ever gets them, Then react based on the hierarchy of what was clicked appropriate.