The Evolution folder selector has a limited keyboard search function.  However, it is limited in that it will not traverse folder hierarchies that are collapsed.  This makes it difficult to perform a Move/Copy to folder without using the mouse.

A few years ago, I implemented a feature for KMail to enhance its folder selection dialog.  The user experience has been well-tested over the years and would make a good enhancement for Evolution.

https://bugs.kde.org/show_bug.cgi?id=113759

I am somewhat familiar with the Evolution code and am willing to spend some time implementing this feature.  However, I would appreciate some help from the Evolution team for feedback and assistance in pushing the patch through the development process.