git-gui: Make usage statement visible on Windows.

On Windows stdout and stderr are not connected to anything so the usage
statement is never shown to the user when an error is made with a command
line like 'git gui browser'. Use a messagebox on windows.

Signed-off-by: Pat Thoyts <patthoyts@users.sourceforge.net>

1 files changed, 7 insertions, 1 deletions

diff --git a/git-gui.sh b/git-gui.sh
index bb104895a..e554043e9 100755
--- a/git-gui.sh
+++ b/git-gui.sh
@@ -2845,7 +2845,13 @@ bind all <$M1B-Key-W> {destroy [winfo toplevel %W]}
 
 set subcommand_args {}
 proc usage {} {
-	puts stderr "usage: $::argv0 $::subcommand $::subcommand_args"
+	set s "usage: $::argv0 $::subcommand $::subcommand_args"
+	if {[tk windowingsystem] eq "win32"} {
+		wm withdraw .
+		tk_messageBox -icon info -title "Usage" -message $s
+	} else {
+		puts stderr $s
+	}
 	exit 1
 }