# Problem using GPanel and child windows in G4P library

**URL:** https://discourse.processing.org/t/problem-using-gpanel-and-child-windows-in-g4p-library/20137
**Category:** Libraries
**Created:** [April 25, 2020, 2:13pm UTC](https://discourse.processing.org/t/problem-using-gpanel-and-child-windows-in-g4p-library/20137 "2020-04-25T14:13:00Z")
**Posts on this page:** 1
**Showing post:** 27

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### Author: ![David](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/david/32/8853_2.png) [@David](https://discourse.processing.org/u/David)
#### Post date: [April 29, 2020, 6:40pm UTC](https://discourse.processing.org/t/problem-using-gpanel-and-child-windows-in-g4p-library/20137/27 "2020-04-29T18:40:38Z")

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I tested it under both Windows 7 (64 bit) and Ubuntu Studio (64 bit), using both the Java AWT and OpenGL. It works fine under WIndows using either renderer, and also under Linux, except when I close the sketch while using OpenGL. Under Linux, I get different error messages when I close the sketch, depending on how I close it (by pressing ESC or clicking on the Exit icon). This may be due to not having a good OpenGL driver installed for Linux, or maybe it’s a problem in Processing itself. I’ve seen a number of posts suggested that the OpenGL renderer is deprecated, but I’m not sure why. But even under Linux using OpenGL, it seems to work fine until I close the sketch.

Attached is one of the error messages I get when closing under Linux using the OpenGL renderer.

 ![ScreenPrint](https://canada1.discourse-cdn.com/flex036/uploads/processingfoundation1/original/2X/e/e92350c8a306c777c310c361a5e9d2fcb4e48904.jpeg)

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