Use the original geometry for floating windows

src/floating.c

@@ -98,7 +98,10 @@ void floating_enable(Con *con, bool automatic) {
     int deco_height = font->height + 5;
 
     DLOG("Original rect: (%d, %d) with %d x %d\n", con->rect.x, con->rect.y, con->rect.width, con->rect.height);
-    nc->rect = con->rect;
+    nc->rect = con->geometry;
+    /* Raise the width/height to at least 75x50 (minimum size for windows) */
+    nc->rect.width = max(nc->rect.width, 75);
+    nc->rect.height = max(nc->rect.height, 50);
     /* add pixels for the decoration */
     /* TODO: don’t add them when the user automatically puts new windows into
      * 1pixel/borderless mode */

src/manage.c

@@ -254,16 +254,15 @@ void manage_window(xcb_window_t window, xcb_get_window_attributes_cookie_t cooki
     if (cwindow->dock)
         want_floating = false;
 
+    /* Store the requested geometry. The width/height gets raised to at least
+     * 75x50 when entering floating mode, which is the minimum size for a
+     * window to be useful (smaller windows are usually overlays/toolbars/…
+     * which are not managed by the wm anyways). We store the original geometry
+     * here because it’s used for dock clients. */
     nc->geometry = (Rect){ geom->x, geom->y, geom->width, geom->height };
 
     if (want_floating) {
-        nc->rect.x = geom->x;
-        nc->rect.y = geom->y;
-        /* We respect the geometry wishes of floating windows, as long as they
-         * are bigger than our minimal useful size (75x50). */
-        nc->rect.width = max(geom->width, 75);
-        nc->rect.height = max(geom->height, 50);
-        DLOG("geometry = %d x %d\n", nc->rect.width, nc->rect.height);
+        DLOG("geometry = %d x %d\n", nc->geometry.width, nc->geometry.height);
         floating_enable(nc, false);
     }
 

testcases/t/53-floating-originalsize.t

@@ -0,0 +1,52 @@
+#!perl
+# vim:ts=4:sw=4:expandtab
+#
+# Test if the requested width/height is set after making the window floating.
+#
+use Time::HiRes qw(sleep);
+use X11::XCB qw(:all);
+use i3test;
+
+my $tmp = get_unused_workspace;
+cmd "workspace $tmp";
+
+my $x = X11::XCB::Connection->new;
+
+# Create a floating window which is smaller than the minimum enforced size of i3
+my $window = $x->root->create_child(
+    class => WINDOW_CLASS_INPUT_OUTPUT,
+    rect => [ 0, 0, 400, 150],
+    background_color => '#C0C0C0',
+);
+
+isa_ok($window, 'X11::XCB::Window');
+
+$window->map;
+
+sleep 0.25;
+
+my ($absolute, $top) = $window->rect;
+
+ok($window->mapped, 'Window is mapped');
+cmp_ok($absolute->{width}, '>', 400, 'i3 raised the width');
+cmp_ok($absolute->{height}, '>', 150, 'i3 raised the height');
+
+cmd 'mode toggle';
+sleep 0.25;
+
+($absolute, $top) = $window->rect;
+
+diag('new width: ' . $absolute->{width});
+diag('new height: ' . $absolute->{height});
+
+# we compare with a tolerance of ± 20 pixels for borders in each direction
+# (overkill, but hey)
+cmp_ok($absolute->{width}, '>', 400-20, 'width now > 380');
+cmp_ok($absolute->{width}, '<', 400+20, 'width now < 420');
+cmp_ok($absolute->{height}, '>', 150-20, 'height now > 130');
+cmp_ok($absolute->{height}, '<', 150+20, 'height now < 170');
+
+#cmp_ok($absolute->{width}, '>=', 75, 'i3 raised the width to 75');
+#cmp_ok($absolute->{height}, '>=', 50, 'i3 raised the height to 50');
+
+done_testing;