diff --git a/community-tests/src/com/intellij/tests/gui/framework/GuiTestCase.java b/community-tests/src/com/intellij/tests/gui/framework/GuiTestCase.java
index 3591008b4f23..21751ccea33f 100644
--- a/community-tests/src/com/intellij/tests/gui/framework/GuiTestCase.java
+++ b/community-tests/src/com/intellij/tests/gui/framework/GuiTestCase.java
@@ -68,6 +68,7 @@ import static junit.framework.Assert.assertNotNull;
 import static org.fest.swing.edt.GuiActionRunner.execute;
 import static org.fest.swing.timing.Pause.pause;
 import static org.fest.util.Strings.quote;
+import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.fail;
 
@@ -91,10 +92,10 @@ public abstract class GuiTestCase {
   @Before
   public void setUp() throws Exception {
     if (!canRunGuiTests()) {
-      // We currently do not support running UI tests in headless environments.
       return;
     }
-    System.setProperty("GuiTestMode", "true");
+
+    assertEquals(System.getProperty("idea.test.guiTestMode"), "true");
 
     Application application = ApplicationManager.getApplication();
     assertNotNull(application); // verify that we are using the IDE's ClassLoader.
diff --git a/platform/testFramework/src/_FirstInSuiteTest.java b/platform/testFramework/src/_FirstInSuiteTest.java
index 671659a77c8b..139606763d8c 100644
--- a/platform/testFramework/src/_FirstInSuiteTest.java
+++ b/platform/testFramework/src/_FirstInSuiteTest.java
@@ -64,7 +64,11 @@ public class _FirstInSuiteTest extends TestCase {
     // in tests EDT inexplicably shuts down sometimes during the first access,
     // which leads to nasty problems in ApplicationImpl which assumes there is only one EDT.
     // so we try to forcibly terminate EDT here to urge JVM to re-spawn new shiny permanent EDT-1
-    TestRunnerUtil.replaceIdeEventQueueSafely();
+
+    //replacing of IdeEventQueue may cause problems with RepaintManager and EventQueue especially on Windows for GUI tests
+    if (!System.getProperty("idea.test.guiTestMode").toLowerCase().equals("true")) {
+      TestRunnerUtil.replaceIdeEventQueueSafely();
+    }
     SwingUtilities.invokeAndWait(() -> System.out.println("EDT is " + Thread.currentThread()));
 
     // force platform JNA load