Re: emacs' headband helpful tips sliced by window edge

[Aloof Petrofsky]

The current behavior is that a tooltip that fits to the right of the
mouse cursor is displayed to the right, otherwise the tip is displayed
to the left.  I think this is rightly called a bug for two reasons:

  1. It causes truncation even if the tip could fit on the screen (if
     the cursor is in the middle of the screen, any tip greater than
     half a screen-width gets truncated).

  2. Whenever it truncates, it lops off the beginning of the tip
     rather than the end.

The patch below fixes both problems: if a tip does not fit to either
side of the cursor, it is placed flush to the left of the screen.

-al


--- xfns.c      2001/12/20 21:26:46     1.1
+++ xfns.c      2001/12/20 21:29:16
@@ -10878,10 +10878,12 @@
 
   if (INTEGERP (left))
     *root_x = XINT (left);
-  else if (*root_x + XINT (dx) + width > FRAME_X_DISPLAY_INFO (f)->width)
+  else if (*root_x + XINT (dx) + width <= FRAME_X_DISPLAY_INFO (f)->width)
+    *root_x += XINT (dx);
+  else if (width + XINT (dx) <= *root_x)
     *root_x -= width + XINT (dx);
   else
-    *root_x += XINT (dx);
+    *root_x = 0;
 }