git-gui: add hotkeys to set widget focus

The user cannot change focus between the list of files, the diff view and
the commit message widgets without using the mouse (clicking either of
the four widgets).

With this patch, the user may set ui focus to the previously selected path
in either the "Unstaged Changes" or "Staged Changes" widgets, using
ALT+1 or ALT+2.

The user may also set the ui focus to the diff view widget with
ALT+3, or to the commit message widget with ALT+4.

This enables the user to select/unselect files, view the diff and create a
commit in git-gui using keyboard-only.

Signed-off-by: Birger Skogeng Pedersen <[email protected]>
Signed-off-by: Pratyush Yadav <[email protected]>

Author: birgersp

git-gui.sh

@@ -2495,7 +2495,7 @@ proc force_first_diff {after} {
 
 proc toggle_or_diff {mode w args} {
 	global file_states file_lists current_diff_path ui_index ui_workdir
-	global last_clicked selected_paths
+	global last_clicked selected_paths file_lists_last_clicked
 
 	if {$mode eq "click"} {
 		foreach {x y} $args break
@@ -2527,6 +2527,8 @@ proc toggle_or_diff {mode w args} {
 	$ui_index tag remove in_sel 0.0 end
 	$ui_workdir tag remove in_sel 0.0 end
 
+	set file_lists_last_clicked($w) $path
+
 	# Determine the state of the file
 	if {[info exists file_states($path)]} {
 		set state [lindex $file_states($path) 0]
@@ -2640,6 +2642,26 @@ proc show_less_context {} {
 	}
 }
 
+proc focus_widget {widget} {
+	global file_lists last_clicked selected_paths
+	global file_lists_last_clicked
+
+	if {[llength $file_lists($widget)] > 0} {
+		set path $file_lists_last_clicked($widget)
+		set index [lsearch -sorted -exact $file_lists($widget) $path]
+		if {$index < 0} {
+			set index 0
+			set path [lindex $file_lists($widget) $index]
+		}
+
+		focus $widget
+		set last_clicked [list $widget [expr $index + 1]]
+		array unset selected_paths
+		set selected_paths($path) 1
+		show_diff $path $widget
+	}
+}
+
 ######################################################################
 ##
 ## ui construction
@@ -3852,6 +3874,14 @@ foreach i [list $ui_index $ui_workdir] {
 }
 unset i
 
+bind .   <Alt-Key-1> {focus_widget $::ui_workdir}
+bind .   <Alt-Key-2> {focus_widget $::ui_index}
+bind .   <Alt-Key-3> {focus $::ui_diff}
+bind .   <Alt-Key-4> {focus $::ui_comm}
+
+set file_lists_last_clicked($ui_index) {}
+set file_lists_last_clicked($ui_workdir) {}
+
 set file_lists($ui_index) [list]
 set file_lists($ui_workdir) [list]