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>

diff --git a/git-gui.sh b/git-gui.sh
index bb104895a94450a2ade7446c8fda52910bae0868..e554043e99ce25bf1066e930a3be67d54b4e0ec5 100755 (executable)
--- 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
 }