Split Client::readTransient into two parts

client.h

@@ -942,6 +942,8 @@ private:
      */
     int quick_tile_mode;
 
+    Xcb::TransientFor fetchTransient() const;
+    void readTransientProperty(Xcb::TransientFor &transientFor);
     void readTransient();
     xcb_window_t verifyTransientFor(xcb_window_t transient_for, bool set);
     void addTransient(Client* cl);

group.cpp

@@ -550,10 +550,14 @@ bool Client::sameAppWindowRoleMatch(const Client* c1, const Client* c2, bool act
  - every window in the group : group()->members()
 */
 
-void Client::readTransient()
+Xcb::TransientFor Client::fetchTransient() const
+{
+    return Xcb::TransientFor(window());
+}
+
+void Client::readTransientProperty(Xcb::TransientFor &transientFor)
 {
     TRANSIENCY_CHECK(this);
-    Xcb::TransientFor transientFor(window());
     xcb_window_t new_transient_for_id = XCB_WINDOW_NONE;
     if (transientFor.getTransientFor(&new_transient_for_id)) {
         m_originalTransientForId = new_transient_for_id;
@@ -565,6 +569,12 @@ void Client::readTransient()
     setTransient(new_transient_for_id);
 }
 
+void Client::readTransient()
+{
+    Xcb::TransientFor transientFor = fetchTransient();
+    readTransientProperty(transientFor);
+}
+
 void Client::setTransient(xcb_window_t new_transient_for_id)
 {
     TRANSIENCY_CHECK(this);

manage.cpp

@@ -103,6 +103,7 @@ bool Client::manage(xcb_window_t w, bool isMapped)
     auto showOnScreenEdgeCookie = fetchShowOnScreenEdge();
     auto colorSchemeCookie = fetchColorScheme();
     auto firstInTabBoxCookie = fetchFirstInTabBox();
+    auto transientCookie = fetchTransient();
     info = new WinInfo(this, m_client, rootWindow(), properties, properties2);
 
     // If it's already mapped, ignore hint
@@ -134,7 +135,7 @@ bool Client::manage(xcb_window_t w, bool isMapped)
     updateAllowedActions(); // Group affects isMinimizable()
 
     modal = (info->state() & NET::Modal) != 0;   // Needs to be valid before handling groups
-    readTransient();
+    readTransientProperty(transientCookie);
     getIcons();
     getWmNormalHints(); // Get xSizeHint
     getMotifHints();