Allow a mouse binding to hide a window, and add a default keybinding for CMS-M3,

so it's hard to press by accident, but there if you need it.

requested (in a way) and tested by johan and todd.

cwm.1

@@ -15,7 +15,7 @@
 .\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 .\"
 .\" The following requests are required for all man pages.
-.Dd $Mdocdate: June 5 2008 $
+.Dd $Mdocdate: June 25 2008 $
 .Dt CWM 1
 .Os
 .Sh NAME
@@ -127,6 +127,8 @@ Toggle a window's membership in the current group.
 Resize a window/select a window.
 .It M-M3
 Lower a window.
+.It CMS-M3
+Hide a window.
 .El
 .Pp
 The options for