keybinds: fix multikey binds breaking after scroll wheel events

[goferito]

Summary

Fixes multikey keybinds (binds / s flag) becoming unresponsive after using the mouse scroll wheel, until a mouse click is performed. Workarounds use ydotool to generate click events when pressing mod-keys, but this generates click events in undesirable places.

Fixes #8699

This bug was introduced in #5966 (multikey keybinds feature, May 2024) and has affected users for over a year.

• Keybinds with 's' flag do not work after scrolling with mouse until a mouse click #11201
• binds combos are not recognized until mouse click #10922
• Confusion with mod key for `binds` and `bind` #10298

Root Cause

Scroll wheel events pass through handleKeybinds() with keysym=0 and pressed=true. Since scroll events have no "release" phase, this 0 gets inserted into m_mkKeys and never removed, corrupting the keysym tracking state and breaking all subsequent multikey bind matching.

Fix

Skip keysym tracking when key.keysym == 0, as these events don't correspond to actual keys and shouldn't affect the pressed-keysym state.

Testing

1. Configure a multikey bind: binds = Alt_R, K, exec, kitty
2. Verify it works
3. Scroll the mouse wheel
4. Verify the bind still works (previously it would fail until a click)

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[goferito]

If someone reads this PR before it gets merged and wants to apply the patch in Arch:

1. Create build directory and get PKGBUILD:

mkdir -p /tmp/hyprland-build && cd /tmp/hyprland-build
curl -sL "https://gitlab.archlinux.org/archlinux/packaging/packages/hyprland/-/raw/main/PKGBUILD" -o PKGBUILD

2. Create patch file fix-binds-scroll.patch:

diff --git a/src/managers/KeybindManager.cpp b/src/managers/KeybindManager.cpp
--- a/src/managers/KeybindManager.cpp
+++ b/src/managers/KeybindManager.cpp
@@ -646,16 +646,20 @@ SDispatchResult CKeybindManager::handleKeybinds(const uint32_t modmask, const SP
   bool            found = false;
   SDispatchResult res;

-    if (pressed) {
-        if (keycodeToModifier(key.keycode))
-            m_mkMods.insert(key.keysym);
-        else
-            m_mkKeys.insert(key.keysym);
-    } else {
-        if (keycodeToModifier(key.keycode))
-            m_mkMods.erase(key.keysym);
-        else
-            m_mkKeys.erase(key.keysym);
+    if (key.keysym != 0) {
+        if (pressed) {
+            if (keycodeToModifier(key.keycode))
+                m_mkMods.insert(key.keysym);
+            else
+                m_mkKeys.insert(key.keysym);
+        } else {
+            if (keycodeToModifier(key.keycode))
+                m_mkMods.erase(key.keysym);
+            else
+                m_mkKeys.erase(key.keysym);
+        }
   }
   for (auto& k : m_keybinds) {

4. Edit PKGBUILD - add to source and sha256sums:
   source=("$_archive.tar.gz::$url/releases/download/v$pkgver/source-v$pkgver.tar.gz" "fix-binds-scroll.patch")
sha256sums=('57b4db99896cad8388482b945b119b206fd7ea94638793b550210be08274d7dd' 'SKIP')

5. Edit PKGBUILD - Add to prepare():
   patch -p1 < "$srcdir/fix-binds-scroll.patch"

6. Build and install:
   makepkg -si

Tested on Hyprland 0.52.2 - my Alt_R binds now work after scrolling!

[vaxerski]

great, can you write a test for this please?