Others have posted feature requests for such a capability. I will point out, however, that if you use the scripted finds that enter find mode and use Set Field to specify the find criteria, you both avoid this issue and also have a scripted find that is easier to work with if you return to such a script and need to modify it after some time has passed. See this thread for examples: Scripted Find Examples
Also when I try to edit a find I...
I would guess that you are using a Mac with OS 10.10 as this is a recently reported issue with that version of the Mac OS. Try scrolling the window next time this happens. It appears that a number of dialogs will appear with the contents scrolled up to the point that they are not visible or not fully visible when the dialog first opens when using a machine with this OS version.
I am using Mac OS 10.10. That was very helpful Phil, thanks.