dot/xinitrc: Overhaul the Emacs/terminal allocation algorithm.

It's now different.  I hadn't given thought to really large monitors
when I came up with the original algorithm.  I think the new one is more
sensible, but we'll see.

diff --git a/dot/xinitrc b/dot/xinitrc
index 7f6d415..5a98ebf 100755 (executable)
--- a/dot/xinitrc
+++ b/dot/xinitrc
@@ -266,18 +266,25 @@ declare -i panelwd=64 xbound=$(( XWIDTH - panelwd ))
 
 ## Choose a width for Emacs.
 ##
-## We'd like it to be as wide as possible, allowing for a column of xterms
-## down the right hand side.  However, I'd prefer a double-width Emacs to a
-## single-width Emacs and xterms.  If it's not going to work at all, a single
-## Emacs column will have to do.  Also, there's a strange thing with Emacs21
-## and the toolbar, so we add on some rows which are later mysteriously
-## subtracted.
-
+## We're going to make a single frame of Emacs, which will be automatically
+## divvied into columns; the rest of the space will be tiled with xterms.  If
+## we have multiple screens, then Emacs can have the first screen and we'll
+## fill the rest with terminals.  Otherwise, we'll try to have N columns of
+## Emacs, and N - 1 columns of xterms; if that doesn't work, we'll make do
+## with N - 2 columns of xterms.
+##
+## So, let W be the available width; let E and T be the widths of an Emacs
+## column (e_colwd) and terminal (t_wd), respectively, and let E0 be the
+## additive width of Emacs's existence (e_hextra).  If we have more than one
+## screen, then instead, let T be zero.  To start out, then, we let N = 1 +
+## floor((W - E - E0)/(E + T)).  If W - E0 - (N + 1) E - (N - 1)*T >= 0, then
+## we increase N by one.
 declare -i lim=XSCR0_WIDTH
 if (( lim > xbound )); then lim=xbound; fi
-declare -i ecols=$(( (lim - t_wd - e_hextra)/e_colwd ))
-if (( ecols < 2 && lim > 2*e_colwd + e_hextra )); then ecols=2
-elif (( ecols < 1 )); then ecols=1
+declare -i twd=t_wd; if (( XNSCR > 1 )); then twd=0; fi
+declare -i ecols=$(( (lim - e_colwd - e_hextra)/(e_colwd + twd) + 1 ))
+if (( lim - e_hextra - (ecols + 1)*e_colwd - (ecols - 1)*twd >= 0 )); then
+  ecols=$(( ecols + 1 ))
 fi
 
 declare -i \