#
#
# patch "lib/perl/Common.pm"
#  from [37679826b5a267078ecc14a5b47eb42eb6733f33]
#    to [8e650608a7fa05dbb21d3d4d1cc290df238244f8]
# 
# patch "lib/perl/History.pm"
#  from [6ebebca72639a26c112139b03876edd543ab7c9d]
#    to [a29e79c181fc8de7480d32eb3dd530a5fdad9c5d]
# 
# patch "mtn-browse"
#  from [8d3222fb76959b757890b771b73c1db6ab922714]
#    to [881f0a6488e4f5b6fa0962fe0d438245e29a0b05]
#
============================================================
--- lib/perl/Common.pm	37679826b5a267078ecc14a5b47eb42eb6733f33
+++ lib/perl/Common.pm	8e650608a7fa05dbb21d3d4d1cc290df238244f8
@@ -87,6 +87,7 @@ sub open_database($$$);
 sub handle_comboxentry_history($$;$);
 sub hex_dump($);
 sub open_database($$$);
+sub program_valid($;$);
 sub register_help_callbacks($@);
 sub run_command($@);
 sub save_as_file($$$);
@@ -1220,6 +1221,71 @@ sub file_glob_to_regexp($)
 #
 ##############################################################################
 #
+#   Routine      - program_valid
+#
+#   Description  - Validate the specified program by seeing if it can be
+#                  found. If a parent window is provided and the specified
+#                  program cannot be found then display a dialog window
+#                  telling the user about the problem.
+#
+#   Data         - $program     : The name of the program or the full path to
+#                                 the program that is to be validated.
+#                  $parent      : The parent window for any dialogs that are
+#                                 to be displayed. This is optional.
+#                  Return Value : True if the program is valid, otherwise
+#                                 false if it is not.
+#
+##############################################################################
+
+
+
+sub program_valid($;$)
+{
+
+    my($program, $parent) = @_;
+
+    my $found;
+
+    if (File::Spec->file_name_is_absolute($program))
+    {
+	$found = 1 if (-x $program || -f ($program . ".exe"));
+    }
+    else
+    {
+	foreach my $dir (File::Spec->path())
+	{
+	    if (-x File::Spec->catfile($dir, $program)
+		|| -f File::Spec->catfile($dir, $program . ".exe"))
+	    {
+		$found = 1;
+		last;
+	    }
+	}
+    }
+
+    # Tell the user that the program can't be found if that is the case and the
+    # caller wants us to inform the user.
+
+    if (! $found && defined($parent))
+    {
+	my $dialog = Gtk2::MessageDialog->new
+	    ($parent,
+	     ["modal"],
+	     "info",
+	     "close",
+	     __x("The program `{program_name}' cannot be found.\n"
+		     . "Is it installed?",
+		 program_name => $program));
+	WindowManager->instance()->allow_input(sub { $dialog->run(); });
+	$dialog->destroy();
+    }
+
+    return $found;
+
+}
+#
+##############################################################################
+#
 #   Routine      - handle_comboxentry_history
 #
 #   Description  - Handle comboboxentry histories. Histories are limited to a
============================================================
--- lib/perl/History.pm	6ebebca72639a26c112139b03876edd543ab7c9d
+++ lib/perl/History.pm	a29e79c181fc8de7480d32eb3dd530a5fdad9c5d
@@ -1954,6 +1954,10 @@ sub external_diffs($$$$$$)
 	$dialog->destroy();
 	return;
     }
+    return unless (program_valid((split(/[[:blank:]]/,
+					$user_preferences->{diffs_application})
+				  )[0],
+				 $parent));
 
     # Generate temporary disk file names.
 
============================================================
--- mtn-browse	8d3222fb76959b757890b771b73c1db6ab922714
+++ mtn-browse	881f0a6488e4f5b6fa0962fe0d438245e29a0b05
@@ -119,12 +119,13 @@ use constant MLS_MANIFEST_ENTRY_COLUMN =
 use constant MLS_AUTHOR_COLUMN         => 3;
 use constant MLS_MANIFEST_ENTRY_COLUMN => 4;
 
-# Constants for various file paths.
+# Constants for various program names and file paths.
 
-use constant UI_DIR => File::Spec->catfile(PREFIX_DIR,
-					   "share",
-					   APPLICATION_NAME,
-					   "glade");
+use constant MONOTONE_VIZ => "monotone-viz";
+use constant UI_DIR       => File::Spec->catfile(PREFIX_DIR,
+						 "share",
+						 APPLICATION_NAME,
+						 "glade");
 
 # The type of window that is going to be managed by this module.
 
@@ -970,10 +971,14 @@ sub monotone_viz_button_clicked_cb($$)
        $db_name,
        @revision_ids);
 
+    # Make sure we have monotone-viz installed first.
+
+    return unless (program_valid(MONOTONE_VIZ, $browser->{window}));
+
     # Build up the monotone-viz command, we need the database name and then
     # optionally the branch and revision ids.
 
-    $cmd = "monotone-viz ";
+    $cmd = MONOTONE_VIZ . " ";
     if (! defined($db_name = $browser->{mtn}->get_db_name()))
     {
 	$browser->{mtn}->get_option(\$db_name, "database");
@@ -1215,6 +1220,7 @@ sub view_button_clicked_cb($$)
 	    ($browser->{window},
 	     ["modal"],
 	     "warning",
+	     "close",
 	     __x("Cannot generate temporary file name:\n{error_message}.",
 		 error_message => $!));
 	$dialog->run();
@@ -1257,10 +1263,12 @@ sub view_button_clicked_cb($$)
     if (defined($mime_details) && $mime_details->{helper_application} ne "")
     {
 
-	# Use the specified helper application, replacing `{file}' with the
-	# real file name.
+	# Use the specified helper application (having validated it first),
+	# replacing `{file}' with the real file name.
 
 	$helper = $mime_details->{helper_application};
+	return unless (program_valid((split(/[[:blank:]]/, $helper))[0],
+				     $browser->{window}));
 	if ($helper =~ m/\{file\}/)
 	{
 	    $helper =~ s/\{file\}/$file_name/g;
@@ -3050,7 +3058,7 @@ sub sigchld_handler()
 	    # If it is an mtn process then close down the relevant object so
 	    # that it will automatically restart when needed.
 
-	    WindowManager->instance()->cond_find
+	    $wm->cond_find
 		(undef,
 		 sub {
 		     my $instance = $_[0];