Hi Mr. Yuri, if Codys dark theme is overwriting the entire UI folder then that's what can cause the most problems with interfering with new features.

For the scene browser resizing, it is probably enough to make sure the file "MainWindowLayout.xml" in the ui folder is not overwritten, make sure that file comes from the current v4 beta's default installation instead of from a previous v4 beta. It has some new attributes in it marking the browser pane to be resizable and if you overwrite it with an old one that will be lost.

But in general overwriting the whole UI folder with files from previous versions can cause these kinds of problems.

- Michael