Add a menu item for writing out a commit to a file.

This just invokes git-diff-tree.  Also changed the readonly entry
widgets in the "write patch" and "generate tag" windows to have
flat relief, so it doesn't look like you should be able to modify
what's in them.

gitk

@@ -426,6 +426,7 @@ proc makewindow {} {
 	-command {diffvssel 1}
     $rowctxmenu add command -label "Make patch" -command mkpatch
     $rowctxmenu add command -label "Create tag" -command mktag
+    $rowctxmenu add command -label "Write commit to file" -command writecommit
 }
 
 # when we make a key binding for the toplevel, make sure
@@ -1821,22 +1822,22 @@ proc mkpatch {} {
     catch {destroy $top}
     toplevel $top
     label $top.title -text "Generate patch"
-    grid $top.title -
+    grid $top.title - -pady 10
     label $top.from -text "From:"
-    entry $top.fromsha1 -width 40
+    entry $top.fromsha1 -width 40 -relief flat
     $top.fromsha1 insert 0 $oldid
     $top.fromsha1 conf -state readonly
     grid $top.from $top.fromsha1 -sticky w
-    entry $top.fromhead -width 60
+    entry $top.fromhead -width 60 -relief flat
     $top.fromhead insert 0 $oldhead
     $top.fromhead conf -state readonly
     grid x $top.fromhead -sticky w
     label $top.to -text "To:"
-    entry $top.tosha1 -width 40
+    entry $top.tosha1 -width 40 -relief flat
     $top.tosha1 insert 0 $newid
     $top.tosha1 conf -state readonly
     grid $top.to $top.tosha1 -sticky w
-    entry $top.tohead -width 60
+    entry $top.tohead -width 60 -relief flat
     $top.tohead insert 0 $newhead
     $top.tohead conf -state readonly
     grid x $top.tohead -sticky w
@@ -1901,18 +1902,18 @@ proc mktag {} {
     catch {destroy $top}
     toplevel $top
     label $top.title -text "Create tag"
-    grid $top.title -
+    grid $top.title - -pady 10
     label $top.id -text "ID:"
-    entry $top.sha1 -width 40
+    entry $top.sha1 -width 40 -relief flat
     $top.sha1 insert 0 $rowmenuid
     $top.sha1 conf -state readonly
     grid $top.id $top.sha1 -sticky w
-    entry $top.head -width 40
+    entry $top.head -width 60 -relief flat
     $top.head insert 0 [lindex $commitinfo($rowmenuid) 0]
     $top.head conf -state readonly
     grid x $top.head -sticky w
     label $top.tlab -text "Tag name:"
-    entry $top.tag -width 40
+    entry $top.tag -width 60
     grid $top.tlab $top.tag -sticky w
     frame $top.buts
     button $top.buts.gen -text "Create" -command mktaggo
@@ -1974,6 +1975,61 @@ proc mktaggo {} {
     mktagcan
 }
 
+proc writecommit {} {
+    global rowmenuid wrcomtop commitinfo wrcomcmd
+
+    set top .writecommit
+    set wrcomtop $top
+    catch {destroy $top}
+    toplevel $top
+    label $top.title -text "Write commit to file"
+    grid $top.title - -pady 10
+    label $top.id -text "ID:"
+    entry $top.sha1 -width 40 -relief flat
+    $top.sha1 insert 0 $rowmenuid
+    $top.sha1 conf -state readonly
+    grid $top.id $top.sha1 -sticky w
+    entry $top.head -width 60 -relief flat
+    $top.head insert 0 [lindex $commitinfo($rowmenuid) 0]
+    $top.head conf -state readonly
+    grid x $top.head -sticky w
+    label $top.clab -text "Command:"
+    entry $top.cmd -width 60 -textvariable wrcomcmd
+    grid $top.clab $top.cmd -sticky w -pady 10
+    label $top.flab -text "Output file:"
+    entry $top.fname -width 60
+    $top.fname insert 0 [file normalize "commit-[string range $rowmenuid 0 6]"]
+    grid $top.flab $top.fname -sticky w
+    frame $top.buts
+    button $top.buts.gen -text "Write" -command wrcomgo
+    button $top.buts.can -text "Cancel" -command wrcomcan
+    grid $top.buts.gen $top.buts.can
+    grid columnconfigure $top.buts 0 -weight 1 -uniform a
+    grid columnconfigure $top.buts 1 -weight 1 -uniform a
+    grid $top.buts - -pady 10 -sticky ew
+    focus $top.fname
+}
+
+proc wrcomgo {} {
+    global wrcomtop
+
+    set id [$wrcomtop.sha1 get]
+    set cmd "echo $id | [$wrcomtop.cmd get]"
+    set fname [$wrcomtop.fname get]
+    if {[catch {exec sh -c $cmd >$fname &} err]} {
+	error_popup "Error writing commit: $err"
+    }
+    catch {destroy $wrcomtop}
+    unset wrcomtop
+}
+
+proc wrcomcan {} {
+    global wrcomtop
+
+    catch {destroy $wrcomtop}
+    unset wrcomtop
+}
+
 proc doquit {} {
     global stopped
     set stopped 100
@@ -1984,6 +2040,7 @@ proc doquit {} {
 set datemode 0
 set boldnames 0
 set diffopts "-U 5 -p"
+set wrcomcmd "git-diff-tree --stdin -p --pretty"
 
 set mainfont {Helvetica 9}
 set textfont {Courier 9}