On a TreeTableView that gets new TreeItems added continuously, at some fast rate, with multiple selection enabled, after selecting an item and then pressing shift to extend the range to a group of items, the selection removes the first item, which is unexpected.

When no more items are added to the TreeTableView or these are added at a low rate (several seconds), then the selection works as expected, if it happens after some time of the last addition.

This issue can be reproduced with any JavaFX version.

To reproduce, run the attached test.

- Select Node 1 (see selectNode1.png)
- Press Shift to extend the range to items Node 1, 2, 3 and 4. Note the selection removes the first item and only three items are selected (see shiftSelectNode4Fails.png)

Wait around 10 seconds (until 100 treeItems have been added), do it again:

- Select Node 1 (see selectNode1.png)
- Press Shift to extend the range to items Node 1, 2, 3 and 4. Note the selection works as expected and four items are selected (see shiftSelectNode4Works.png).