dnd/seat: avoid sending button events during a dnd op

fixes #8781

src/managers/SeatManager.cpp

@@ -281,7 +281,7 @@ void CSeatManager::sendPointerMotion(uint32_t timeMs, const Vector2D& local) {
 }
 
 void CSeatManager::sendPointerButton(uint32_t timeMs, uint32_t key, wl_pointer_button_state state_) {
-    if (!state.pointerFocusResource)
+    if (!state.pointerFocusResource || PROTO::data->dndActive())
         return;
 
     for (auto const& s : seatResources) {

src/protocols/core/DataDevice.cpp

@@ -808,5 +808,5 @@ void CWLDataDeviceProtocol::renderDND(PHLMONITOR pMonitor, timespec* when) {
 }
 
 bool CWLDataDeviceProtocol::dndActive() {
-    return dnd.currentSource && dnd.mouseButton /* test a member of the state to ensure it's also present */;
+    return dnd.currentSource;
 }