Ok So you use to be able to have open as many plugins as you wanted at the same time. At least I know it was a lot more than 1.
With the new sonar Platinum I can not have more than 1 plugin open at the same time.. is there a way to change this setting.. This is one of the reasons I have 4 screens and I would like to be able to continue my workflow to maximize my time. It just a big waste of time to have to keep reopening things..

Try this:
Preferences -->  VST Settings
Don't select "Recycle Plugin Windows"

Like above, or use the ctrl key as you select other plugs

oh sweet thanks guys... 
 

You also have to "Pin" the windows...

THambrecht
Try this:
Preferences -->  VST Settings
Don't select "Recycle Plugin Windows"

In SPlat 2017.05 I have to open Preferences, check it, close Preference, reopen Preferences and uncheck it for it to work right.

soens
 
In SPlat 2017.05 I have to open Preferences, check it, close Preference, reopen Preferences and uncheck it for it to work right.

I noticed this got broken recently. Your trick seems to work. Thanks.

Notecrusher

soens
 
In SPlat 2017.05 I have to open Preferences, check it, close Preference, reopen Preferences and uncheck it for it to work right.

I noticed this got broken recently. Your trick seems to work. Thanks.

Interesting.  I tried this, and now Melodyne is not kicking out any plug windows, and the "Pin" icon is automatically "lit" when i first open the plugin window.  That solved the problem completely on all fronts.