Steps to Reproduce

Run attached zul + java sample

Set the browser zoom level to 90% (also can reproduce on 100%, but less frequently)

Load the page

Resize the window to ~40 rows on screen

reload the page

While the page is loading, scroll down continuously

Click a cell. If the cell blue selection square matches the row number blue selection highlight, then you didn't reproduce the issue. try again from "reload the page"

Current Result

Some rows are missing, the selection box is desynced from the row selection highlight by that many rows.

May or may not cause other JS issues

May or may not cause typing values to a new cell to write the input value to a number of rows above based on missing rows.

see screenshots attached:

#1: selection square is not synced with actual selection

#2 missing rows : (the excel document doesn't have hidden rows)

sample of possible JS errors:

Uncaught TypeError: Cannot read properties of null (reading 'isMerged')
    at init._doMouseclick (zss.wpd:39080:14)
    at init._doMouseup (zss.wpd:38838:9)
    at init.doMouseUp_ (zss.wpd:19080:14)
    at _doEvt (zk.wpd:26479:39)
    at HTMLDocument.<anonymous> (zk.wpd:26641:3)
    at HTMLDocument.dispatch (zk.wpd:5410:27)
    at elemData.handle (zk.wpd:5062:28)
_doMouseclick	@	zss.wpd:39080
_doMouseup	@	zss.wpd:38838
doMouseUp_	@	zss.wpd:19080
_doEvt	@	zk.wpd:26479
(anonymous)	@	zk.wpd:26641
dispatch	@	zk.wpd:5410
elemData.handle	@	zk.wpd:5062

Expected Result

No missing rows, not secondary issues

Debug Information

The sample contain a "performance lowering pseudo-sleep function" because the user must scroll while rendering cells.

The issue can be reproduced without it, but it would have made creating a reproducing excel sheet way more time-consuming (it would require a lot of expensive features like large data, lot of references, merged cells and styles)

The issue happens if the user scrolls after the rows from the initial rendering have been added to the DOM, but while the rows with wrapping cells and auto height are still calculating their heights.

(cell height calculation cause the active range to be pruned)

the issue is timing sensitive, so you may need to reload and scroll multiple times to reproduce. 

reported on 5.9.0, also reproduced on 5.10.0

Workaround

In the zul file attached, commented out