git-gui: Option to default new branches to match tracking branches

In some workflows users will want to almost always just create a new
local branch that matches a remote branch.  In this type of workflow
it is handy to have the new branch dialog default to "Match Tracking
Branch" and "Starting Revision"-Tracking Branch", with the focus in
the branch filter field.  This can save users working on this type
of workflow at least two mouse clicks every time they create a new
local branch or switch to one with a fast-forward.
Signed-off-by: NShawn O. Pearce <spearce@spearce.org>

git-gui.sh

@@ -1339,6 +1339,7 @@ set default_config(merge.verbosity) 2
 set default_config(user.name) {}
 set default_config(user.email) {}
 
+set default_config(gui.matchtrackingbranch) false
 set default_config(gui.pruneduringfetch) false
 set default_config(gui.trustmtime) false
 set default_config(gui.diffcontext) 5

lib/branch_create.tcl

@@ -93,13 +93,14 @@ constructor dialog {} {
 	pack $w.options.checkout -anchor nw
 	pack $w.options -anchor nw -fill x -pady 5 -padx 5
 
+	trace add variable @name_type write [cb _select]
+
 	set name $repo_config(gui.newbranchtemplate)
+	if {[is_config_true gui.matchtrackingbranch]} {
+		set name_type match
+	}
 
-	bind $w <Visibility> "
-		grab $w
-		$w_name icursor end
-		focus $w_name
-	"
+	bind $w <Visibility> [cb _visible]
 	bind $w <Key-Escape> [list destroy $w]
 	bind $w <Key-Return> [cb _create]\;break
 	tkwait window $w
@@ -361,4 +362,18 @@ method _validate {d S} {
 	return 1
 }
 
+method _select {args} {
+	if {$name_type eq {match}} {
+		$w_rev pick_tracking_branch
+	}
+}
+
+method _visible {} {
+	grab $w
+	if {$name_type eq {user}} {
+		$w_name icursor end
+		focus $w_name
+	}
+}
+
 }

lib/choose_rev.tcl

@@ -159,6 +159,10 @@ method get {} {
 	}
 }
 
+method pick_tracking_branch {} {
+	set revtype trck
+}
+
 method get_tracking_branch {} {
 	set i [$w_list curselection]
 	if {$i eq {} || $revtype ne {trck}} {

lib/option.tcl

@@ -191,6 +191,7 @@ proc do_options {} {
 
 		{b gui.trustmtime  {Trust File Modification Timestamps}}
 		{b gui.pruneduringfetch {Prune Tracking Branches During Fetch}}
+		{b gui.matchtrackingbranch {Match Tracking Branches}}
 		{i-0..99 gui.diffcontext {Number of Diff Context Lines}}
 		{t gui.newbranchtemplate {New Branch Name Template}}
 		} {