Product Version: NetBeans IDE 6.1 RC2 (Build 200804170002)
Java: 1.6.0_05; Java HotSpot(TM) Client VM 10.0-b19
System: Linux version 2.6.22-14-generic running on i386; UTF-8; en_US (nb)

Product Version: NetBeans IDE Dev (Build 200804210001)
Java: 1.5.0_14; Java HotSpot(TM) Client VM 1.5.0_14-b03
System: Linux version 2.6.22-14-generic running on i386; UTF-8; en_US (nb)

1. Create a new Java application with a JFrame, open a form Visual Design for the JFrame.
2. Go to palette and click a MenuItem component (you do not need a menu bar to demonstrate this minor issue).
3. Scroll over the JFrame form in the visual design 
-> You can see the MenuItem preview by your cursor

4. Click the left or right mouse button over the JFrame form (left mouse button tries to insert the item in the place,
but it is not possible at the moment, right mouse button is - in general - used to cancel the insertion of the component
in the form)
-> Component is not inserted (correct), the MenuItem preview disappears (correct as well)

5. Now, move a mouse cursor above some other view (palette, output view, projects view, navigator... just outside the
VD), do not click or something...
6. Move the cursor back over the JFrame
-> MenuItem preview is back by the cursor, as if you didn't try to insert/cancel insertion before (as if you didn't do
step 4)...

This works on Menu, Menu Item, Menu Item/Radio-button and MenuItem/Check-box from the Swing Menus category in the
palette. The problem might be in the fact that the item in the palette remains selected after the step 4. Other
components work fine and the item in the Palette view is always deselected after the right-click (or left-click on a
wrong place).