zName = "diff-command";
  }
  return db_get(zName, zDefault);
}

/* A Tcl/Tk script used to render diff output.
*/
static const char zDiffScript[] =
@ package require Tk
@ 
@ array set CFG {
@   TITLE      {Fossil Diff}

@   LN_COL_BG  #dddddd
@   LN_COL_FG  #444444
@   TXT_COL_BG #ffffff
@   TXT_COL_FG #000000
@   MKR_COL_BG #444444
@   MKR_COL_FG #dddddd

@   CHNG_BG    #d0d0ff
@   ADD_BG     #c0ffc0
@   RM_BG      #ffc0c0
@   HR_FG      #888888
@   HR_PAD_TOP 4
@   HR_PAD_BTM 8
@   FONTS      {{DejaVu Sans Mono} Consolas Monaco fixed}
@   FONT_SIZE  9
@   PADX       5
@   WIDTH      80
@   HEIGHT     45
@ }
@ 
@ if {![namespace exists ttk]} {
@   interp alias {} ::ttk::scrollbar {} ::scrollbar
@   interp alias {} ::ttk::menubutton {} ::menubutton
@ }
@ 
@ proc dehtml {x} {
@   set x [regsub -all {<[^>]*>} $x {}]
@   return [string map {&amp; & &lt; < &gt; > &#39; ' &quot; \"} $x]
@ }
@ 
@ proc cols {} {
@   return [list .lnA .txtA .mkr .lnB .txtB]
@ }
@ 
@ proc colType {c} {
@   regexp {[a-z]+} $c type
@   return $type
@ }
@ 
@ proc readDiffs {cmd} {
@   global gDiffs
@   set in [open $cmd r]

@   set idx -1
@   while {[gets $in line] != -1} {
@     if {![regexp {^=+\s+(.*?)\s+=+$} $line all fn]} {
@       continue
@     }
@     
@     if {[string compare -length 6 [gets $in] "<table"]} {
@       continue
@     }
@     
@     incr idx
@     .files.menu add radiobutton -variable gIdx -value $idx -label $fn \
@       -command "viewDiff $idx"
@     array set widths {txt 0 ln 0 mkr 0}
@     
@     foreach c [cols] {
@       while {[gets $in] ne "<pre>"} continue
@       set type [colType $c]
@       set str {}
@       while {[set line [gets $in]] ne "</pre>"} {
@         set len [string length [dehtml $line]]
@         if {$len > $widths($type)} {
@           set widths($type) $len
@         }
@         append str $line\n
@       }
@       
@       set str [string range $str 0 end-1]
@       set colData {}
@       set re {<span class="diff([a-z]+)">([^<]*)</span>}
@       # Use \r as separator since it can't appear in the diff output (it gets
@       # converted to a space).
@       set str [regsub -all $re $str "\r\\1\r\\2\r"]
@       foreach {pre class mid} [split $str \r] {
@         if {$class ne ""} {
@           lappend colData [dehtml $pre] - [dehtml $mid] [list $class -]
@         } else {
@           lappend colData [dehtml $pre] -
@         }
@       }
@       set gDiffs($idx,$c) $colData
@     }
@     
@     foreach {type width} [array get widths] {
@       set gDiffs($idx,$type-width) $width
@     }
@   }
@   close $in
@ }
@ 
@ proc viewDiff {idx} {
@   global gDiffs
@   .files config -text [.files.menu entrycget $idx -label]
@   
@   foreach c [cols] {
@     $c config -state normal
@     $c delete 1.0 end
@     foreach {content tag} $gDiffs($idx,$c) {
@       $c insert end $content $tag
@     }
@   }
@   
@   foreach c {.lnA .lnB .mkr} {
@     $c config -width $gDiffs($idx,[colType $c]-width)
@   }
@   
@   # Add whitespace to equalize line lengths.
@   regexp {\d+} [.txtA index {end -1c}] numLines
@   set width $gDiffs($idx,txt-width)
@   foreach c {.txtA .txtB} {
@     for {set ln 1} {$ln <= $numLines} {incr ln} {
@       regexp {\d+$} [$c index $ln.end] len
@       $c insert $ln.end [string repeat " " [expr {$width-$len}]] ws
@     }
@   }
@   
@   foreach c [cols] {
@     $c config -state disabled
@   }
@ }
@ 
@ proc cycleDiffs {{inc 1}} {
@   global gIdx
@   .files.menu invoke [expr {($gIdx+$inc) % ([.files.menu index last]+1)}]
@ }
@ 
@ proc scrollSync {axis sbs first last} {
@   foreach c [cols] {
@     $c ${axis}view moveto $first
@   }
@   foreach sb $sbs {
@     if {$first <= 0 && $last >= 1} {
@       grid remove $sb
@     } else {
@       grid $sb
@       $sb set $first $last
@     }
@   }
@ }
@ 
@ proc copyText {c} {
@   set txt ""
@   # Copy selection without excess trailing whitespace
@   $c tag config ws -elide 1
@   catch {
@     $c tag add sel sel.first sel.last
@     set txt [selection get]
@   }
@   $c tag config ws -elide 0
@   clipboard clear
@   clipboard append $txt
@ }
@ 
@ wm withdraw .
@ wm title . $CFG(TITLE)
@ wm iconname . $CFG(TITLE)
@ bind . <q> exit
@ bind . <Tab> {cycleDiffs; break}
@ bind . <<PrevWindow>> {cycleDiffs -1; break}
@ bind . <Return> {
@   event generate .files <1>
@   event generate .files <ButtonRelease-1>
@   break
@ }

@ foreach {key axis args} {
@   Up    y {scroll -5 units}
@   Down  y {scroll 5 units}
@   Left  x {scroll -5 units}
@   Right x {scroll 5 units}
@   Prior y {scroll -1 page}
@   Next  y {scroll 1 page}
@   Home  y {moveto 0}
@   End   y {moveto 1}
@ } {
@   bind . <$key> ".txtA ${axis}view $args; break"
@   bind . <Shift-$key> continue
@ }
@ 
@ ::ttk::menubutton .files -menu .files.menu
@ menu .files.menu -tearoff 0
@ readDiffs $cmd
@ if {[.files.menu index 0] eq "none"} {
@   tk_messageBox -type ok -title $CFG(TITLE) -message "No changes"
@   exit
@ }
@ 
@ foreach side {A B} {
@   set ln .ln$side
@   text $ln
@   $ln tag config - -justify right
@   
@   set txt .txt$side
@   text $txt -width $CFG(WIDTH) -height $CFG(HEIGHT) -wrap none \
@     -xscroll {scrollSync x {.sbxA .sbxB}}
@   foreach tag {add rm chng} {
@     $txt tag config $tag -background $CFG([string toupper $tag]_BG)
@     $txt tag lower $tag
@   }
@   bind $txt <<Copy>> {copyText %W; break}
@   bind $txt <<Cut>> {copyText %W; break}
@ }
@ text .mkr
@ 
@ font create mono -family courier -size $CFG(FONT_SIZE)
@ foreach font $CFG(FONTS) {
@   if {[lsearch -exact [font families] $font] != -1} {
@      font config mono -family $font
@      break
@   }
@ }
@ foreach c [cols] {
@   set keyPrefix [string toupper [colType $c]]_COL_
@   $c config -bg $CFG(${keyPrefix}BG) -fg $CFG(${keyPrefix}FG) -borderwidth 0 \
@     -font mono -padx $CFG(PADX) -insertontime 0 -yscroll {scrollSync y .sby}
@   $c tag config hr -spacing1 $CFG(HR_PAD_TOP) -spacing3 $CFG(HR_PAD_BTM) \
@      -foreground $CFG(HR_FG)
@   bindtags $c ". $c Text all"
@   bind $c <1> {focus %W}
@ }
@ 
@ ::ttk::scrollbar .sby -command {.txtA yview} -orient vertical
@ ::ttk::scrollbar .sbxA -command {.txtA xview} -orient horizontal
@ ::ttk::scrollbar .sbxB -command {.txtA xview} -orient horizontal
@ 
@ grid rowconfigure . 1 -weight 1
@ grid columnconfigure . 1 -weight 1
@ grid columnconfigure . 4 -weight 1
@ grid .files -columnspan 6
@ eval grid [cols] .sby -sticky nsew
@ grid .sbxA -row 2 -column 0 -columnspan 2 -sticky ew
@ grid .sbxB -row 2 -column 3 -columnspan 2 -sticky ew
@ 
@ .files.menu invoke 0
@ wm deiconify .
;

/*
** Show diff output in a Tcl/Tk window, in response to the --tk option
** to the diff command.
** 
** Steps:
** (1) Write the Tcl/Tk script used for rendering into a temp file.
** (2) Invoke "wish" on the temp file using fossil_system().
** (3) Delete the temp file.
*/
void diff_tk(const char *zSubCmd, int firstArg){
  int i;
  Blob script;
  char *zTempFile;
  char *zCmd;
  blob_zero(&script);
  blob_appendf(&script, "set cmd {| \"%/\" %s --html -y -i -v",
               g.nameOfExe, zSubCmd);
  for(i=firstArg; i<g.argc; i++){
    const char *z = g.argv[i];
    if( z[0]=='-' ){
      if( strglob("*-html",z) ) continue;
      if( strglob("*-y",z) ) continue;
      if( strglob("*-i",z) ) continue;