Steps to Reproduce

run the attached example frozen-issues.zul in chrome / FF / edge

use theme: breeze

1. scroll horizontally to the right
2. hover the grid rows

Current Result

1a). the borders between the column headers disappear
1b). (Chrome)some contents become visible between the frozen grid borders (highlighted in red)

2a) chrome/edge the hover styles overlap the frozen columns
2b) FF similar effect as in 1b) when hovering a row

Expected Result

no leaking styles between borders or above frozen cells