From f5d264287432b7b2c3458624bf3fbc6fd065221f Mon Sep 17 00:00:00 2001
From: attila <attila@juce.com>
Date: Fri, 1 Jul 2022 21:15:00 +0200
Subject: [PATCH] Linux:  Fix resizing issue with the PopupMenu

Previously opening a PopupMenu and then clicking somewhere outside
the application would cause the mouse button representation to be
stuck in a down state.
---
 .../native/x11/juce_linux_XWindowSystem.cpp   | 39 +++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/modules/juce_gui_basics/native/x11/juce_linux_XWindowSystem.cpp b/modules/juce_gui_basics/native/x11/juce_linux_XWindowSystem.cpp
index 5ef06a28d0..da1a27308e 100644
--- a/modules/juce_gui_basics/native/x11/juce_linux_XWindowSystem.cpp
+++ b/modules/juce_gui_basics/native/x11/juce_linux_XWindowSystem.cpp
@@ -413,6 +413,31 @@ namespace Keys
     static bool capsLock = false;
     static char keyStates [32];
     static constexpr int extendedKeyModifier = 0x10000000;
+    static bool modifierKeysAreStale = false;
+
+    static void refreshStaleModifierKeys()
+    {
+        if (modifierKeysAreStale)
+        {
+            XWindowSystem::getInstance()->getNativeRealtimeModifiers();
+            modifierKeysAreStale = false;
+        }
+    }
+
+    // Call this function when only the mouse keys need to be refreshed e.g. when the event
+    // parameter already has information about the keys.
+    static void refreshStaleMouseKeys()
+    {
+        if (modifierKeysAreStale)
+        {
+            const auto oldMods = ModifierKeys::currentModifiers;
+            XWindowSystem::getInstance()->getNativeRealtimeModifiers();
+            ModifierKeys::currentModifiers = oldMods.withoutMouseButtons()
+                                                    .withFlags (ModifierKeys::currentModifiers.withOnlyMouseButtons()
+                                                                                              .getRawFlags());
+            modifierKeysAreStale = false;
+        }
+    }
 }
 
 const int KeyPress::spaceKey              = XK_space         & 0xff;
@@ -2448,6 +2473,18 @@ ModifierKeys XWindowSystem::getNativeRealtimeModifiers() const
 
     ModifierKeys::currentModifiers = ModifierKeys::currentModifiers.withoutMouseButtons().withFlags (mouseMods);
 
+    // We are keeping track of the state of modifier keys and mouse buttons with the assumption that
+    // for every mouse down we are going to receive a mouse up etc.
+    //
+    // This assumption is broken when getNativeRealtimeModifiers() is called. If for example we call
+    // this function when the mouse cursor is in another application and the mouse button happens to
+    // be down, then its represented state in currentModifiers may remain down indefinitely, since
+    // we aren't going to receive an event when it's released.
+    //
+    // We mark this state in this variable, and we can restore synchronization when our window
+    // receives an event again.
+    Keys::modifierKeysAreStale = true;
+
     return ModifierKeys::currentModifiers;
 }
 
@@ -3310,6 +3347,7 @@ void XWindowSystem::handleWindowMessage (LinuxComponentPeer* peer, XEvent& event
 void XWindowSystem::handleKeyPressEvent (LinuxComponentPeer* peer, XKeyEvent& keyEvent) const
 {
     auto oldMods = ModifierKeys::currentModifiers;
+    Keys::refreshStaleModifierKeys();
 
     char utf8 [64] = { 0 };
     juce_wchar unicodeChar = 0;
@@ -3540,6 +3578,7 @@ void XWindowSystem::handleButtonReleaseEvent (LinuxComponentPeer* peer, const XB
 void XWindowSystem::handleMotionNotifyEvent (LinuxComponentPeer* peer, const XPointerMovedEvent& movedEvent) const
 {
     updateKeyModifiers ((int) movedEvent.state);
+    Keys::refreshStaleMouseKeys();
 
     auto& dragState = dragAndDropStateMap[peer];