clean up, remove isNimbus

platform/platform-api/src/com/intellij/ui/components/panels/NonOpaquePanel.java

-/*
- * Copyright 2000-2011 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 2000-2017 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.
 package com.intellij.ui.components.panels;
 
-import com.intellij.util.ui.UIUtil;
-
 import javax.swing.*;
 import java.awt.*;
 
@@ -54,18 +50,9 @@ public class NonOpaquePanel extends Wrapper {
   public void setOpaque(boolean isOpaque) {
     super.setOpaque(isOpaque);
     setDoubleBuffered(false);
-
-    if (!isOpaque && UIUtil.isUnderNimbusLookAndFeel()) {
-      if (UIUtil.isUnderNimbusLookAndFeel()) {
-        setBackground(UIUtil.TRANSPARENT_COLOR);
-      }
-    }
   }
 
   public static void setTransparent(JComponent c) {
     c.setOpaque(false);
-    if (UIUtil.isUnderNimbusLookAndFeel()) {
-      c.setBackground(UIUtil.TRANSPARENT_COLOR);
-    }
   }
 }