supports image viewer 2

Common/Testing/Tcl/rtImageTest.tcl

@@ -83,7 +83,9 @@ if {$validImageFound != 0} {
 	   set threshold 5
        }
       if {[info commands viewer] == "viewer"} {
-         rt_w2if SetInput [viewer GetImageWindow]
+         if {[catch {rt_w2if SetInput [viewer GetImageWindow]}]} {
+            rt_w2if SetInput [viewer GetRenderWindow]
+         }
          viewer Render
       } else {
          if {[info commands imgWin] == "imgWin"} {
@@ -91,7 +93,9 @@ if {$validImageFound != 0} {
             imgWin Render
          } else {
             if {[info exists viewer]} {
-               rt_w2if SetInput [$viewer GetImageWindow]
+               if {[catch {rt_w2if SetInput [$viewer GetImageWindow]}]} {
+                  rt_w2if SetInput [$viewer GetRenderWindow]
+               }
             }
          }
       }