Allow only one RED instance

[hxseven]

I got this request by email:

I find very useful your program and really appreciate your efforts.
I would like to point you one possible 'problem'.
I found it very confusing the fact that the program allows for multiple instances.
It may happen that I have minimised the running instance and simply start a new one, unaware or oblivious of the previous one being still active. That sometimes can give unexpected behaviour to the user.
I think that this kind of application is better limited to a single instance.
What do you think about this?
However, thanks always for your work.

I think that is a valid point. I will have a look on how complicated it is to implement this.
Does anybody have any arguments against this? I'm open for discussion :)

[jsytniak]

Could also check for a running instance and notify via prompt that an instance is already running and ask to start a new instance. Note, checking for instance may need to check for instances within sessions.