The tree followed the lead row by index, so expanding or collapsing a folder above the selection shifted the index and scrolled back to the selected row. It now scrolls when the lead changes. A lead whose row has not loaded yet is kept pending and scrolled to once when the row appears, so preselected rows and async loads still come into view.
Covers keyboard navigation, speed search, Select Opened File and autoscroll from source, which all still scroll to the new lead.
Co-authored-by: a-rookie-of-C-language <[email protected]>