gitk: Add a context menu for file list entries

At the moment this just has two entries, which allow you to add the file
that you clicked on to the list of filenames to highlight, or replace
the list with the file.
Signed-off-by: NPaul Mackerras <paulus@samba.org>

gitk

@@ -879,6 +879,7 @@ proc makewindow {} {
     bind $cflist <1> {sel_flist %W %x %y; break}
     bind $cflist <B1-Motion> {sel_flist %W %x %y; break}
     bind $cflist <ButtonRelease-1> {treeclick %W %x %y}
+    bind $cflist <Button-3> {pop_flist_menu %W %X %Y %x %y}
 
     set maincursor [. cget -cursor]
     set textcursor [$ctext cget -cursor]
@@ -916,6 +917,14 @@ proc makewindow {} {
 	-command cobranch
     $headctxmenu add command -label "Remove this branch" \
 	-command rmbranch
+
+    global flist_menu
+    set flist_menu .flistctxmenu
+    menu $flist_menu -tearoff 0
+    $flist_menu add command -label "Highlight this too" \
+	-command {flist_hl 0}
+    $flist_menu add command -label "Highlight this only" \
+	-command {flist_hl 1}
 }
 
 # mouse-2 makes all windows scan vertically, but only the one
@@ -1499,6 +1508,33 @@ proc sel_flist {w x y} {
     }
 }
 
+proc pop_flist_menu {w X Y x y} {
+    global ctext cflist cmitmode flist_menu flist_menu_file
+    global treediffs diffids
+
+    set l [lindex [split [$w index "@$x,$y"] "."] 0]
+    if {$l <= 1} return
+    if {$cmitmode eq "tree"} {
+	set e [linetoelt $l]
+	if {[string index $e end] eq "/"} return
+    } else {
+	set e [lindex $treediffs($diffids) [expr {$l-2}]]
+    }
+    set flist_menu_file $e
+    tk_popup $flist_menu $X $Y
+}
+
+proc flist_hl {only} {
+    global flist_menu_file highlight_files
+
+    set x [shellquote $flist_menu_file]
+    if {$only || $highlight_files eq {}} {
+	set highlight_files $x
+    } else {
+	append highlight_files " " $x
+    }
+}
+
 # Functions for adding and removing shell-type quoting
 
 proc shellquote {str} {