tests/constraints.tcl [testmenubarheight]: correct condition that tests existence of C-level command

Author: 1minus1is0

tests/constraints.tcl

@@ -246,9 +246,9 @@ namespace eval tk {
 	# got moved to the requested location should use a y coordinate larger than the
 	# height of the menubar (normally 23 pixels) and an x coordinate larger than the
 	# width of the dock, if it happens to be on the left.
-	# testmenubarheight deals with this issue but may not be available from the test
-	# environment, therefore provide a fallback here
-	if {[llength [info procs testmenubarheight]] == 0} {
+	# The C-level command "testmenubarheight" deals with this issue but it may
+	# not be available on each platform. Therefore, provide a fallback here.
+	if {[llength [info commands testmenubarheight]] == 0} {
 	    if {[tk windowingsystem] ne "aqua"} {
 		# Windows may overlap the menubar
 		proc testmenubarheight {} {