Rewrite most of grab_menu in grab.c (it was partly 9wm code).

This should work functionally the same, with a few simplifications.

Changes:
- we don't care if you're holding another button when you release the
  menu key if you don't want to select anything, move off the menu.
- remove the hysteresis from the menu selection (before you had to move
  more than three pixels onto a new menu entry before it selected it)
- simplify a lot of the selection code
- kill dead code.
- do what the XXX comment said and cache the screensize (i may tweak
  this later).

As far as I can tell, the only code remaining from 9wm is the list of
fonts in calmwm.c. Others appear to concur.

ok marc@, looked over and tested by a few others. Reminders from okan@.

calmwm.c

@@ -50,7 +50,6 @@ static char gray_bits[] = {0x02, 0x01};
 /* List borrowed from 9wm/rio */
 char *tryfonts[] = {
 	"9x15bold",
-	"blit",
 	"*-lucidatypewriter-bold-*-14-*-75-*",
 	"*-lucidatypewriter-medium-*-12-*-75-*",
 	"fixed",
@@ -161,9 +160,7 @@ x_setup(char *display_name)
 	Cursor_resize = XCreateFontCursor(X_Dpy, XC_bottom_right_corner);
 	/* (used to be) XCreateFontCursor(X_Dpy, XC_hand1); */
 	Cursor_select = XCreateFontCursor(X_Dpy, XC_hand1);
-/* 	Cursor_select = cursor_bigarrow(Curscreen); */
 	Cursor_default = XCreateFontCursor(X_Dpy, XC_X_cursor);
-/* 	Cursor_default = cursor_bigarrow(Curscreen); */
 	Cursor_question = XCreateFontCursor(X_Dpy, XC_question_arrow);
 }
 
@@ -288,9 +285,6 @@ x_setupscreen(struct screen_ctx *sc, u_int which)
 	rootattr.event_mask = ChildMask|PropertyChangeMask|EnterWindowMask|
 	    LeaveWindowMask|ColormapChangeMask|ButtonMask;
 
-	/* Set the root cursor to a nice obnoxious arrow :-) */
-/* 	rootattr.cursor = cursor_bigarrow(sc); */
-
 	XChangeWindowAttributes(X_Dpy, sc->rootwin,
 	    /* CWCursor| */CWEventMask, &rootattr);