Fix incorrect geometry when border or scroll bar is enabled

When border or scroll bar is enabled the -geometry flag isn’t quite
respected.  For example, starting the terminal via ‘urxvt -geometry
80x24 -pe tabbedex’ might result in internal tab having only 77
columns and 23 lines.  This is caused by root window being sized with
the assumption that there is no border or scroll bar even if they are
present in the tabs.

Fixes: #44

tabbedex

@@ -920,11 +920,26 @@ sub copy_properties {
                                                                $atom);
 
       # fix up size hints
-      if ($atom == $wm_normal_hints) {
+      if ($atom == $wm_normal_hints && $root->{tabheight}) {
+         # typedef struct {
+         #         long flags;                  /* 0 */
+         #         int x, y;                    /* 1, 2 */ /* Obsolete */
+         #         int width, height;           /* 3, 4 */ /* Obsolete */
+         #         int min_width, min_height;   /* 5, 6 */
+         #         int max_width, max_height;   /* 7, 8 */
+         #         int width_inc, height_inc;   /* 9, 10 */
+         #         struct {
+         #                 int x; /* numerator */
+         #                 int y; /* denominator */
+         #         } min_aspect, max_aspect;    /* 11, 12, 13, 14 */
+         #         int base_width, base_height; /* 15, 16 */
+         #         int win_gravity;             /* 17 */
+         # } XSizeHints;
+         #
+         # (Don’t ask me how this works with long and int types.  Somehow it
+         # does – mina86).
          my (@hints) = unpack "l!*", $items;
-
          $hints[$_] += $root->{tabheight} for (4, 6, 16);
-
          $items = pack "l!*", @hints;
       }
 
@@ -1122,11 +1137,14 @@ sub init {
    $root->{resource} = [map $root->resource ("+$_"),
                             0 .. urxvt::NUM_RESOURCES - 1];
 
+   $root->{hpadding} = $root->{vpadding} = 2 * $root->int_bwidth;
    $root->resource (int_bwidth => 0);
    $root->resource (pty_fd => -1);
 
    if (defined(my $key = $urxvt::OPTION{scrollBar})) {
-      $root->{option}{$key} = $root->option($key, 0);
+      if ($root->{option}{$key} = $root->option($key, 0)) {
+         $root->{hpadding} += $root->get_scrollbar_thickness;
+      }
    }
    # Disable ‘intensityStyles’ so that bold, blink etc. specified in tabbar
    # styles don’t affect the colours.
@@ -1162,13 +1180,69 @@ sub init {
    $root->{timer} = urxvt::timer->new->cb ( sub { $root->refresh; } );
 }
 
+# Figures out the thickness of scroll bar.  This is based on scrollBar_t::setup
+# code and written with the assumption that urxvt was compiled with all styles
+# enabled.
+sub get_scrollbar_thickness {
+	my ($root) = @_;
+
+	my $style = $root->resource('scrollstyle') || '';
+	my $width;
+
+	if ($style =~ /^next/i) {
+		$style = 'next';
+		$width = 19;  # SB_WIDTH_NEXT
+	} elsif ($style =~ /^xterm/i) {
+		$width = 15;  # SB_STYLE_XTERM
+	} elsif ($style =~ /^plain/i) {
+		$width = 7;  # SB_WIDTH_PLAIN
+	} else {
+		$style = 'rxvt';
+		$width = 10;  # SB_WIDTH_RXVT
+	}
+
+	# Relevant excerpt from the C++ code:
+	#
+	#  thickness = term->rs[Rs_scrollBar_thickness];
+	#  if (style != SB_STYLE_NEXT)	/* dishonour request - for now */
+	#    if (thickness && (i = atoi (thickness)) >= SB_WIDTH_MINIMUM)
+	#      width = min (i, SB_WIDTH_MAXIMUM);
+	if ($style ne 'next') {
+		my $thickness = $root->resource('scrollBar_thickness');
+		if ($thickness && $thickness >= 5) {
+			# SB_WIDTH_MAXIMUM == 100
+			$width = $thickness < 100 ? $thickness : 100;
+		}
+	}
+
+	my $key = $urxvt::OPTION{scrollBar_floating};
+	if ($style eq 'rxvt' && defined $key && !$root->option($key)) {
+		$width += 2;
+	}
+
+	$width
+}
+
 _on start => sub {
    my ($root) = @_;
 
    $root->{maxtabheight} =
       $root->int_bwidth + $root->fheight + $root->lineSpace;
    $root->{tabheight} = $root->{autohide} ? 0 : $root->{maxtabheight};
 
+   # Root window is always created without scroll bar or border which means that
+   # it’s sized without any space allocated for those elements.  However, tabs
+   # may have those options enabled which makes means that they end up with less
+   # usable space than user requested. To account for that, enlarge the root to
+   # make space for the border and scroll bar.
+   my $hpadding = delete $root->{hpadding};
+   my $vpadding = delete $root->{vpadding};
+   if ($hpadding || $vpadding || $root->{tabheight}) {
+      my $w = $root->width + $hpadding;
+      my $h = $root->height + $vpadding + $root->{tabheight};
+      $root->XMoveResizeWindow($root->parent, 0, 0, $w, $h);
+   }
+
    $root->cmd_parse(delete $root->{init_cmd});
 
    my @argv = $root->argv;