Regrab buttons on mode change (#5554)

Unfortunately, grabbing / ungrabbing doesn't seem to work correctly in
xvfb so we can't really test this.

I also fixed the deduplication code in bindings_get_buttons_to_grab().

release-notes/bugfixes/3-bindsym-button-mode

@@ -0,0 +1 @@
+fix mouse bindings in modes

src/bindings.c

@@ -631,6 +631,7 @@ void switch_mode(const char *new_mode) {
         current_binding_mode = mode->name;
         translate_keysyms();
         grab_all_keys(conn);
+        regrab_all_buttons(conn);
 
         /* Reset all B_UPON_KEYRELEASE_IGNORE_MODS bindings to avoid possibly
          * activating one of them. */
@@ -1008,7 +1009,7 @@ bool load_keymap(void) {
 int *bindings_get_buttons_to_grab(void) {
     /* Let's make the reasonable assumption that there's no more than 25
      * buttons. */
-    int num_max = 25;
+    const int num_max = 25;
 
     int buffer[num_max];
     int num = 0;
@@ -1034,12 +1035,17 @@ int *bindings_get_buttons_to_grab(void) {
         }
 
         /* Avoid duplicates. */
+        bool exists = false;
         for (int i = 0; i < num; i++) {
-            if (buffer[i] == button)
-                continue;
+            if (buffer[i] == button) {
+                exists = true;
+                break;
+            }
         }
 
-        buffer[num++] = button;
+        if (!exists) {
+            buffer[num++] = button;
+        }
     }
     buffer[num++] = 0;
 

testcases/t/320-mouse-bindings.t

@@ -0,0 +1,89 @@
+#!perl
+# vim:ts=4:sw=4:expandtab
+#
+# Please read the following documents before working on tests:
+# • https://build.i3wm.org/docs/testsuite.html
+#   (or docs/testsuite)
+#
+# • https://build.i3wm.org/docs/lib-i3test.html
+#   (alternatively: perldoc ./testcases/lib/i3test.pm)
+#
+# • https://build.i3wm.org/docs/ipc.html
+#   (or docs/ipc)
+#
+# • http://onyxneon.com/books/modern_perl/modern_perl_a4.pdf
+#   (unless you are already familiar with Perl)
+#
+# Test button bindsyms
+use i3test i3_config => <<EOT;
+# i3 config file (v4)
+font -misc-fixed-medium-r-normal--13-120-75-75-C-70-iso10646-1
+focus_follows_mouse no
+
+for_window[class="mark_A"] mark A
+for_window[class="mark_B"] mark B
+for_window[class="mark_C"] mark C
+for_window[class="mark_D"] mark D
+
+bindsym button1 --whole-window [con_mark=A] focus
+bindsym button2 --whole-window [con_mark=B] focus
+
+bindsym button4 --whole-window [con_mark=B] focus
+mode "testmode" {
+    bindsym button4 --whole-window [con_mark=C] focus
+    bindsym button5 --whole-window [con_mark=D] focus
+}
+
+default_border pixel 0
+
+EOT
+use i3test::XTEST;
+
+sub button {
+    my ($button, $window, $msg) = @_;
+    xtest_button_press($button, 5, 5);
+    xtest_button_release($button, 5, 5);
+    xtest_sync_with_i3;
+
+    local $Test::Builder::Level = $Test::Builder::Level + 1;
+    is_focus($window, $msg);
+}
+
+sub is_focus {
+    my ($window, $msg) = @_;
+    local $Test::Builder::Level = $Test::Builder::Level + 1;
+    is($x->input_focus, $window->id, $msg);
+}
+
+# Leftmost window is focused on button presses that have no binding
+my $L = open_window;
+my $A = open_window(wm_class => 'mark_A');
+my $B = open_window(wm_class => 'mark_B');
+is_focus($B, 'sanity check');
+is_focus(open_window, 'sanity check, other window');
+
+button(1, $A, 'button 1 binding');
+button(1, $A, 'button 1 binding, again');
+button(2, $B, 'button 2 binding');
+button(1, $A, 'button 1 binding');
+button(3, $L, 'button 3, no binding');
+
+# Test modes, see #4539
+# Unfortunately, grabbing / ungrabbing doesn't seem to work correctly in xvfb
+# so we can't really test this.
+
+my $C = open_window(wm_class => 'mark_C');
+my $D = open_window(wm_class => 'mark_D');
+
+button(4, $B, 'button 4 binding outside mode');
+button(5, $L, 'button 5 no binding outside mode');
+
+cmd 'mode testmode';
+button(4, $C, 'button 4 binding inside mode');
+button(5, $D, 'button 5 binding inside mode');
+
+cmd 'mode default';
+button(4, $B, 'button 4 binding outside mode');
+button(5, $L, 'button 5 no binding outside mode');
+
+done_testing;