update ubuntu instruction

arch · arch · commit f7105048b802 · 2021-07-10T18:03:53.000+02:00
diff --git a/docs/app/docs/user-guide/build.md b/docs/app/docs/user-guide/build.md
@@ -32,4 +32,4 @@ make docs
 
 Now you can run the code direct with `python3 funscript-editor.py` or install install a pip package with `make all`.
 
-**NOTE:** In my Ubuntu test setup the UI hangs at all `cv2.waitKey()` lines in the code. Remove this part of the code solve the issue but the then i could not select an ROI, because the mouse event do not work. When i hard-code a trackingbox, the ui work but this is not usable. So we need future investigation for this problem. For now i recommend an Arch based Linux.
+**NOTE:** In my Ubuntu test setup the UI hangs because Ubuntu use the GTK Backend while the Arch Linux OpenCV library was compiled with QT (see `python3 -c "import cv2; print(cv2.getBuildInformation())"` output). To use the Application on Ubuntu you have to compile OpenCV + OpenCV contrib with `-D WITH_QT=ON` flag from source.

Original file line number	Diff line number	Diff line change
`@@ -32,4 +32,4 @@ make docs`
`32`	`32`
`33`	`33`	Now you can run the code direct with `python3 funscript-editor.py` or install install a pip package with `make all`.
`34`	`34`
`35`		-NOTE: In my Ubuntu test setup the UI hangs at all `cv2.waitKey()` lines in the code. Remove this part of the code solve the issue but the then i could not select an ROI, because the mouse event do not work. When i hard-code a trackingbox, the ui work but this is not usable. So we need future investigation for this problem. For now i recommend an Arch based Linux.
	`35`	+NOTE: In my Ubuntu test setup the UI hangs because Ubuntu use the GTK Backend while the Arch Linux OpenCV library was compiled with QT (see `python3 -c "import cv2; print(cv2.getBuildInformation())"` output). To use the Application on Ubuntu you have to compile OpenCV + OpenCV contrib with `-D WITH_QT=ON` flag from source.