IDEA-66333 Quick documentation lookup on mouse hover

Don't overwrite documentation for the element under cursor by documentation for the element under caret

platform/lang-impl/src/com/intellij/codeInsight/documentation/DockablePopupManager.java

@@ -150,7 +150,7 @@ public abstract class DockablePopupManager<T extends JComponent & Disposable> {
       if (myAutoUpdateRequest == null) {
         myAutoUpdateRequest = new Runnable() {
           public void run() {
-            if (myProject.isDisposed()) return;
+            if (!myAutoUpdateDocumentation || myProject.isDisposed()) return;
 
             AsyncResult<DataContext> asyncResult = DataManager.getInstance().getDataContextFromFocus();
             DataContext dataContext = asyncResult.getResult();

platform/lang-impl/src/com/intellij/codeInsight/documentation/DocumentationManager.java

@@ -175,6 +175,10 @@ public class DocumentationManager extends DockablePopupManager<DocumentationComp
     return myToolWindow != null;
   }
   
+  public void setAllowContentUpdateFromContext(boolean allow) {
+    myAutoUpdateDocumentation = allow;
+  }
+  
   /**
    * Asks to show quick doc for the target element.
    * 

platform/lang-impl/src/com/intellij/codeInsight/documentation/QuickDocOnMouseOverManager.java

@@ -211,6 +211,7 @@ public class QuickDocOnMouseOverManager {
     { 
       return;
     }
+    allowUpdateFromContext(false);
     closeQuickDocIfPossible();
     myActiveElements.put(editor, targetElementUnderMouse);
     myDelayedQuickDocInfo = new DelayedQuickDocInfo(documentationManager, editor, targetElementUnderMouse, elementUnderMouse);
@@ -221,12 +222,7 @@ public class QuickDocOnMouseOverManager {
 
   private void closeQuickDocIfPossible() {
     myAlarm.cancelAllRequests();
-    WeakReference<DocumentationManager> ref = myDocumentationManager;
-    if (ref == null) {
-      return;
-    }
-
-    DocumentationManager docManager = ref.get();
+    DocumentationManager docManager = getDocManager();
     if (docManager == null) {
       return;
     }
@@ -240,6 +236,27 @@ public class QuickDocOnMouseOverManager {
     myDocumentationManager = null;
   }
 
+  private void allowUpdateFromContext(boolean allow) {
+    DocumentationManager documentationManager = getDocManager();
+    if (documentationManager != null) {
+      documentationManager.setAllowContentUpdateFromContext(allow);
+    }
+  }
+
+  @Nullable
+  private DocumentationManager getDocManager() {
+    WeakReference<DocumentationManager> ref = myDocumentationManager;
+    if (ref == null) {
+      return null;
+    }
+
+    DocumentationManager docManager = ref.get();
+    if (docManager == null) {
+      return null;
+    }
+    return docManager;
+  }
+  
   private static class DelayedQuickDocInfo {
 
     @NotNull public final DocumentationManager docManager;
@@ -333,6 +350,7 @@ public class QuickDocOnMouseOverManager {
   private class MyCaretListener implements CaretListener {
     @Override
     public void caretPositionChanged(CaretEvent e) {
+      allowUpdateFromContext(true);
       closeQuickDocIfPossible(); 
     }
   }