Make Front panel front most

Once the VI is completed go to VI properties or press Ctrl + I

In the VI properties, change the categories to Windows Appearance 
  
Select the Custom Option and click Customize







In the Customize Window Appearance window, Under Window Behavior select Modal

Click OK and Save your VI.

Once you have completed the process, Test the VI. This will make your VI to be the top most of all the other panels.

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