Unmerging cells sets the value to each of the previously merged cells

[IvanDanchev]

Bug report

The root cause of the issue is the fact that internally, we are populating all merged cells (not only the first one) with the same typed value. As a result, when the first three cells on the first row are merged, the =COUNTA(A1:C1) function will return 3, while in Excel it will return 1.

Reproduction of the problem

Reproducible in the demos. Screencast.

1. Select several cells and merge them.
2. Enter a value in the new cell.
3. Unmerge the cells.

Current behavior

The value is set to all previously merged cells.

Expected/desired behavior

The value is set only to the first cell in the range of merged cells.

Environment

• Kendo UI version: 2019.3.1023
• jQuery version: x.y
• Browser: [all]

[veselints]

Also reported in Ticket ID: 1405609

[PekoPPT]

This issue could be also observed with COUNTBLANK, SUBTOTAL, and COUNT (range operations).
Ticket ID: 1406172