diff --git a/platform/xdebugger-impl/src/com/intellij/xdebugger/impl/frame/XWatchesViewImpl.java b/platform/xdebugger-impl/src/com/intellij/xdebugger/impl/frame/XWatchesViewImpl.java
index ce96c769d2eb..d411b83079d3 100644
--- a/platform/xdebugger-impl/src/com/intellij/xdebugger/impl/frame/XWatchesViewImpl.java
+++ b/platform/xdebugger-impl/src/com/intellij/xdebugger/impl/frame/XWatchesViewImpl.java
@@ -1,6 +1,4 @@
-/*
- * Copyright 2000-2017 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
- */
+// Copyright 2000-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 package com.intellij.xdebugger.impl.frame;
 
 import com.intellij.ide.DataManager;
@@ -11,6 +9,7 @@ import com.intellij.openapi.CompositeDisposable;
 import com.intellij.openapi.Disposable;
 import com.intellij.openapi.actionSystem.*;
 import com.intellij.openapi.actionSystem.impl.ActionToolbarImpl;
+import com.intellij.openapi.application.ApplicationManager;
 import com.intellij.openapi.ide.CopyPasteManager;
 import com.intellij.openapi.util.Disposer;
 import com.intellij.openapi.util.EmptyRunnable;
@@ -218,6 +217,7 @@ public class XWatchesViewImpl extends XVariablesView implements DnDNativeTarget,
 
   @Override
   public void addWatchExpression(@NotNull XExpression expression, int index, final boolean navigateToWatchNode) {
+    ApplicationManager.getApplication().assertIsDispatchThread();
     XDebugSession session = getSession(getTree());
     myRootNode.addWatchExpression(session != null ? session.getCurrentStackFrame() : null, expression, index, navigateToWatchNode);
     updateSessionData();
@@ -276,6 +276,7 @@ public class XWatchesViewImpl extends XVariablesView implements DnDNativeTarget,
 
   @Override
   public void removeWatches(List<? extends XDebuggerTreeNode> nodes) {
+    ApplicationManager.getApplication().assertIsDispatchThread();
     List<? extends WatchNode> children = myRootNode.getWatchChildren();
     int minIndex = Integer.MAX_VALUE;
     List<XDebuggerTreeNode> toRemove = new ArrayList<>();
@@ -299,6 +300,7 @@ public class XWatchesViewImpl extends XVariablesView implements DnDNativeTarget,
 
   @Override
   public void removeAllWatches() {
+    ApplicationManager.getApplication().assertIsDispatchThread();
     myRootNode.removeAllChildren();
     updateSessionData();
   }
@@ -362,20 +364,13 @@ public class XWatchesViewImpl extends XVariablesView implements DnDNativeTarget,
   public void drop(DnDEvent aEvent) {
     Object object = aEvent.getAttachedObject();
     if (object instanceof XValueNodeImpl[]) {
-      final XValueNodeImpl[] nodes = (XValueNodeImpl[])object;
-      for (XValueNodeImpl node : nodes) {
-        node.getValueContainer().calculateEvaluationExpression().done(expression -> {
-          if (expression != null) {
-            //noinspection ConstantConditions
-            addWatchExpression(expression, -1, false);
-          }
-        });
+      for (XValueNodeImpl node : (XValueNodeImpl[])object) {
+        DebuggerUIUtil.addToWatches(this, node);
       }
     }
     else if (object instanceof EventInfo) {
       String text = ((EventInfo)object).getTextForFlavor(DataFlavor.stringFlavor);
       if (text != null) {
-        //noinspection ConstantConditions
         addWatchExpression(XExpressionImpl.fromText(text), -1, false);
       }
     }
diff --git a/platform/xdebugger-impl/src/com/intellij/xdebugger/impl/ui/DebuggerUIUtil.java b/platform/xdebugger-impl/src/com/intellij/xdebugger/impl/ui/DebuggerUIUtil.java
index 12232fa2d583..812f156f1e31 100644
--- a/platform/xdebugger-impl/src/com/intellij/xdebugger/impl/ui/DebuggerUIUtil.java
+++ b/platform/xdebugger-impl/src/com/intellij/xdebugger/impl/ui/DebuggerUIUtil.java
@@ -39,6 +39,7 @@ import com.intellij.xdebugger.impl.XDebuggerUtilImpl;
 import com.intellij.xdebugger.impl.breakpoints.XBreakpointBase;
 import com.intellij.xdebugger.impl.breakpoints.ui.BreakpointsDialogFactory;
 import com.intellij.xdebugger.impl.breakpoints.ui.XLightBreakpointPropertiesPanel;
+import com.intellij.xdebugger.impl.frame.XWatchesView;
 import com.intellij.xdebugger.impl.ui.tree.XDebuggerTree;
 import com.intellij.xdebugger.impl.ui.tree.XDebuggerTreeState;
 import com.intellij.xdebugger.impl.ui.tree.nodes.XValueNodeImpl;
@@ -382,6 +383,14 @@ public class DebuggerUIUtil {
     }
   }
 
+  public static void addToWatches(@NotNull XWatchesView watchesView, @NotNull XValueNodeImpl node) {
+    node.getValueContainer().calculateEvaluationExpression().onSuccess(expression -> {
+      if (expression != null) {
+        invokeLater(() -> watchesView.addWatchExpression(expression, -1, false));
+      }
+    });
+  }
+
   public static void registerActionOnComponent(String name, JComponent component, Disposable parentDisposable) {
     AnAction action = ActionManager.getInstance().getAction(name);
     action.registerCustomShortcutSet(action.getShortcutSet(), component, parentDisposable);
diff --git a/platform/xdebugger-impl/src/com/intellij/xdebugger/impl/ui/tree/actions/XAddToWatchesTreeAction.java b/platform/xdebugger-impl/src/com/intellij/xdebugger/impl/ui/tree/actions/XAddToWatchesTreeAction.java
index d0998b353573..cd28f8798b6a 100644
--- a/platform/xdebugger-impl/src/com/intellij/xdebugger/impl/ui/tree/actions/XAddToWatchesTreeAction.java
+++ b/platform/xdebugger-impl/src/com/intellij/xdebugger/impl/ui/tree/actions/XAddToWatchesTreeAction.java
@@ -1,18 +1,4 @@
-/*
- * Copyright 2000-2017 JetBrains s.r.o.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
+// Copyright 2000-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 package com.intellij.xdebugger.impl.ui.tree.actions;
 
 import com.intellij.openapi.actionSystem.AnActionEvent;
@@ -40,12 +26,7 @@ public class XAddToWatchesTreeAction extends XDebuggerTreeActionBase {
   protected void perform(final XValueNodeImpl node, @NotNull final String nodeName, final AnActionEvent e) {
     final XWatchesView watchesView = getWatchesView(e);
     if (watchesView != null) {
-      node.getValueContainer().calculateEvaluationExpression()
-        .done(expression -> {
-        if (expression != null) {
-          watchesView.addWatchExpression(expression, -1, true);
-        }
-      });
+      DebuggerUIUtil.addToWatches(watchesView, node);
     }
   }