DataTable: stickyHeader + multiple selection makes "Select All" inactive

[erickdeoliveiraleal]

1) Environment

• PrimeFaces version: 6.3-SNAPSHOT
• Does it work on the newest released PrimeFaces version? Version? yes
• Does it work on the newest sources in GitHub? no
• Application server + version: wildfly
• Affected browsers:

2) Expected behavior

it should be toggleable.

3) Actual behavior

checkbox is always disabled if stickyHeader = true

4) Steps to reproduce

5) Sample Project

https://github.com/erickdeoliveiraleal/primefaces-test/tree/selectModeMultiple

[tandraschko]

PR would be great.

[Rapster]

I can reproduce it on the showcase, once sticky header showing up, the checkbox is working

[Rapster]

This one is a regression as it's working on 6.2

UPDATE
Not sure actually, I tried on my company app and the app is runnning under 6.2 but we overrided setupStickyHeader so the sticky contains columns header and paginator, so the bug could be there from the start

[mertsincan]

Related to #4469