Where's the Width button in Reaper ?

Unlike pan functionality, "width" isn't a standard control that you'll find in most DAWs. Usually, "width" processing is done using M/S, delay, or phase-based processing. If you hunt around you should be able to find some plug-ins that perform this function.

My personal favorite stereo-imaging processor is Dr. MS, which uses M/S processing to create stereo width. There are TONS of plugs out there that will perform similar types of processing though.
 
Unlike pan functionality, "width" isn't a standard control that you'll find in most DAWs. Usually, "width" processing is done using M/S, delay, or phase-based processing. If you hunt around you should be able to find some plug-ins that perform this function.

My personal favorite stereo-imaging processor is Dr. MS, which uses M/S processing to create stereo width. There are TONS of plugs out there that will perform similar types of processing though.

Well from the OP I understood that it really isn't a stereo enhancing feature, more like a control that lets you adjust the stereo width of a stereo track, between 100% L-R and complete mono...


and speaking of which, i have no idea if such a feature exists in reaper, neither have I ever needed such a feature. I'm guessing you'll just have to search for a plug-in that does the thing
 
Right click the pan knob on any track, and select Stereo Pan as the panning mode and the width knob should show up for that track. If you prefer this panning mode theres an option in Preferences to make it the default.
 
I don't use it, but from what I understand it basically sets the boundaries of how far left and right the channels are on a stereo track. So pan center and width 100% means hard left and hard right. Pan center and width 50% means 50% left and 50% right. I'm not exactly sure how it reacts when you start messing around with the pan and width on a stereo track though, I guess that's where it gets interesting???
 
With the RADO theme:

width.JPG
 
To add to FarBy0ndMetal, I think the option to make your preferred panning mode a standard is in the project settings. You can save it as "project default".
 
its the same in reaper. they are separate functions. click the routing button(the one with MASTER SND RCV I/O on it) and there is your width function separate from your pan. its also right under pan in your envelop listings if you want to automate it