Allow terminal positioning algorithm to be configurable

Previous change "Take into account WM decorations when tiling (Github pull
request #66) (thanks to Andrew Stevenson)" has caused problems on some
systems but improved tiling on others, so make the algorithm configurable
to use the original one (default) or the new style.

To be revisited when all the window handling code is moved into a separate
module

Changes

@@ -3,6 +3,7 @@
 - Correct a logic bug around the --debug option (Github issue #75)
 - Fix 'Re-add closed windows' not using the correct username (Github issue #72)
 - Update copyright year
+- Make WM decorations algorithm configurable as causes problems on some systems (Debian bug 842965, re Github pull request #66) (thanks to Tony Mancill)
 
 4.08 2016-10-18 Duncan Ferguson <duncan_ferguson@user.sf.net>
 - Add perl-5.8, 5.10 and 5.12 to Travis-CI automated testing

lib/App/ClusterSSH.pm

@@ -1001,18 +1001,26 @@ sub retile_hosts {
     # now find the size of the window decorations
     if ( !exists( $self->config->{internal_terminal_wm_decoration_left} ) ) {
 
-        # use the first window as exemplary
-        my ($wid) = $servers{ ( keys(%servers) )[0] }{wid};
+   # Debian #842965 (https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=842965)
+   # disable behavior added in https://github.com/duncs/clusterssh/pull/66
+   # unless explicitly enabled with auto_wm_decoration_offsets => yes
 
-        if ( defined($wid) ) {
+        if ( $self->config->{auto_wm_decoration_offsets} =~ /yes/i ) {
 
-            # get the WM decoration sizes
-            (   $self->config->{internal_terminal_wm_decoration_left},
-                $self->config->{internal_terminal_wm_decoration_right},
-                $self->config->{internal_terminal_wm_decoration_top},
-                $self->config->{internal_terminal_wm_decoration_bottom}
-                )
-                = X11::Protocol::WM::get_net_frame_extents( $xdisplay, $wid );
+            # use the first window as exemplary
+            my ($wid) = $servers{ ( keys(%servers) )[0] }{wid};
+
+            if ( defined($wid) ) {
+
+                # get the WM decoration sizes
+                (   $self->config->{internal_terminal_wm_decoration_left},
+                    $self->config->{internal_terminal_wm_decoration_right},
+                    $self->config->{internal_terminal_wm_decoration_top},
+                    $self->config->{internal_terminal_wm_decoration_bottom}
+                    )
+                    = X11::Protocol::WM::get_net_frame_extents( $xdisplay,
+                    $wid );
+            }
         }
 
         # in case the WM call failed we set some defaults

lib/App/ClusterSSH/Config.pm

@@ -104,6 +104,8 @@ my %default_config = (
 
     send_menu_xml_file => $ENV{HOME} . '/.clusterssh/send_menu',
 
+    auto_wm_decoration_offsets => "no",    # Debian #842965
+
     # don't set username here as takes precendence over ssh config
     user => '',
 );

lib/App/ClusterSSH/Getopt.pm

@@ -633,6 +633,11 @@ would replace the <Alt-n> with the client's name in each window.}
         'L<--autoquit>',
     );
 
+    output '=item auto_wm_decoration_offsets = no';
+    output $self->loc(
+        'Enable or disable alternative algorithm for calculating terminal positioning.',
+    );
+
     output '=item comms = ' . $self->parent->config->{comms};
     output $self->loc(
         'Sets the default communication method (initially taken from the name of the program, but can be overridden here).'

t/15config.t

@@ -118,6 +118,9 @@ Readonly::Hash my %default_config => {
 
     send_menu_xml_file => $ENV{HOME} . '/.clusterssh/send_menu',
 
+    # Debian #842965
+    auto_wm_decoration_offsets => "no",
+
     # other bits inheritted from App::ClusterSSH::Base
     lang => 'en',
     user => '',
@@ -534,6 +537,7 @@ trap {
 my $expected = qq{# Configuration dump produced by "cssh -d"
 auto_close=5
 auto_quit=yes
+auto_wm_decoration_offsets=no
 console=console
 console_args=
 console_position=