add api to check if document is visible in other windows

use new	api for the viewspace checking

apps/lib/kateapp.cpp

@@ -657,3 +657,13 @@ void KateApp::remoteMessageReceived(quint32, QByteArray message)
         activeMainWindow()->activateView(doc);
     }
 }
+
+bool KateApp::documentVisibleInOtherWindows(KTextEditor::Document *doc, KateMainWindow *window) const
+{
+    for (auto win : m_mainWindows) {
+        if (win != window && win->viewManager()->viewspaceCountForDoc(doc) > 0) {
+            return true;
+        }
+    }
+    return false;
+}

apps/lib/kateapp.h

@@ -226,6 +226,16 @@ public:
 
     int mainWindowID(KateMainWindow *window);
 
+    /**
+     * Has the given document tabs/views inside main windows
+     * other then the given one?
+     *
+     * @param doc document to check
+     * @param window window to check
+     * @return is this document visible as tab/view/... in any other window?
+     */
+    bool documentVisibleInOtherWindows(KTextEditor::Document *doc, KateMainWindow *window) const;
+
     /**
      * some stuff for the dcop API
      */

apps/lib/kateviewmanager.cpp

@@ -1172,20 +1172,7 @@ int KateViewManager::viewspaceCountForDoc(KTextEditor::Document *doc) const
 
 bool KateViewManager::docOnlyInOneViewspace(KTextEditor::Document *doc) const
 {
-    auto count = viewspaceCountForDoc(doc);
-    if (count > 1) {
-        return false;
-    }
-
-    std::vector<KateMainWindow *> mainWindows;
-    const auto mws = KateApp::self()->mainWindows();
-    for (auto *mw : mws) {
-        auto w = qobject_cast<KateMainWindow *>(mw->window());
-        if (w && w != m_mainWindow) {
-            count += w->viewManager()->viewspaceCountForDoc(doc);
-        }
-    }
-    return count == 1;
+    return (viewspaceCountForDoc(doc) == 1) && !KateApp::self()->documentVisibleInOtherWindows(doc, m_mainWindow);
 }
 
 void KateViewManager::setShowUrlNavBar(bool show)