Use the combined geometry of children when setting a split container to floating (+testcase) (Thanks mseed)

Fixes #332

testcases/t/55-floating-split-size.t

@@ -0,0 +1,70 @@
+#!perl
+# vim:ts=4:sw=4:expandtab
+#
+# Test to see if i3 combines the geometry of all children in a split container
+# when setting the split container to floating
+#
+use X11::XCB qw(:all);
+use Time::HiRes qw(sleep);
+use i3test;
+
+BEGIN {
+    use_ok('X11::XCB::Window');
+}
+
+my $x = X11::XCB::Connection->new;
+my $i3 = i3("/tmp/nestedcons");
+
+my $tmp = get_unused_workspace;
+cmd "workspace $tmp";
+
+#####################################################################
+# open a window with 200x80
+#####################################################################
+
+my $first = $x->root->create_child(
+    class => WINDOW_CLASS_INPUT_OUTPUT,
+    rect => [ 0, 0, 200, 80],
+    background_color => '#FF0000',
+);
+
+$first->map;
+
+sleep 0.25;
+
+#####################################################################
+# Open a second window with 300x90
+#####################################################################
+
+my $second = $x->root->create_child(
+    class => WINDOW_CLASS_INPUT_OUTPUT,
+    rect => [ 0, 0, 300, 90],
+    background_color => '#00FF00',
+);
+
+$second->map;
+
+sleep 0.25;
+
+#####################################################################
+# Set the parent to floating
+#####################################################################
+cmd 'nop setting floating';
+cmd 'level up';
+cmd 'mode floating';
+
+#####################################################################
+# Get geometry of the first floating node (the split container)
+#####################################################################
+
+my @nodes = @{get_ws($tmp)->{floating_nodes}};
+my $rect = $nodes[0]->{rect};
+
+# we compare the width with ± 20 pixels for borders
+cmp_ok($rect->{width}, '>', 500-20, 'width now > 480');
+cmp_ok($rect->{width}, '<', 500+20, 'width now < 520');
+# we compare the height with ± 40 pixels for decorations
+cmp_ok($rect->{height}, '>', 90-40, 'width now > 50');
+cmp_ok($rect->{height}, '<', 90+40, 'width now < 130');
+
+done_testing;