git-gui: add possibility to open currently selected file

...in the default associated app (e.g. in a text editor / IDE).

Many times there's the need to quickly open a source file (the one you're
looking at in Git GUI) in the predefined text editor / IDE. Of course,
the file can be searched for in your preferred file manager or directly
in the text editor, but having the option to directly open the current
file from Git GUI would be just faster. This change enables just that by:
 - Diff header path context menu -> Open;
 - or double-clicking the diff header path.

One "downside" of the approach is that executable files will be run
and not opened for editing.

Signed-off-by: Zoli Szabó <[email protected]>

Author: zoliszabo

git-gui.sh

@@ -2248,8 +2248,8 @@ proc do_git_gui {} {
 	}
 }
 
-proc do_explore {} {
-	global _gitworktree
+# Get the system-specific explorer app/command.
+proc get_explorer {} {
 	set explorer {}
 	if {[is_Cygwin] || [is_Windows]} {
 		set explorer "explorer.exe"
@@ -2259,9 +2259,25 @@ proc do_explore {} {
 		# freedesktop.org-conforming system is our best shot
 		set explorer "xdg-open"
 	}
+	return $explorer
+}
+
+proc do_explore {} {
+	global _gitworktree
+	set explorer [get_explorer]
 	eval exec $explorer [list [file nativename $_gitworktree]] &
 }
 
+# Trigger opening a file (relative to the working tree) by the default
+# associated app of the OS (e.g. a text editor or IDE).
+# FIXME: What about executables (will be run, not opened for editing)?
+proc do_file_open {file} {
+	global _gitworktree
+	set explorer [get_explorer]
+	set full_file_path [file join $_gitworktree $file]
+	eval exec $explorer [list [file nativename $full_file_path]] &
+}
+
 set is_quitting 0
 set ret_code    1
 
@@ -3530,8 +3546,14 @@ $ctxm add command \
 			-type STRING \
 			-- $current_diff_path
 	}
+$ctxm add command \
+	-label [mc Open] \
+	-command {
+		do_file_open $current_diff_path
+	}
 lappend diff_actions [list $ctxm entryconf [$ctxm index last] -state]
 bind_button3 .vpane.lower.diff.header.path "tk_popup $ctxm %X %Y"
+bind .vpane.lower.diff.header.path <Double-1> {do_file_open $current_diff_path}
 
 # -- Diff Body
 #