[Bug]: The chat dialog scrollbar is not working on drag nor on click

### Describe the Bug

If I try to drag the scrollbar or click the up/down buttons no scrolling occurs. Only the mouse wheel scroll works.

### Reproduce the bug

Start a replay, with enough chats messages and try the different scroll possibilities in the chat dialog

### Screenshots

_No response_

### Additional context

_No response_

Start by reproducing the issue in a replay with enough chat messages to show the chat dialog scrollbar. Trace the chat dialog and its scrollbar handling from the replay UI, then verify that dragging the scrollbar and clicking its up/down buttons both scroll the messages, alongside mouse-wheel scrolling.

Written by the indexing model from the issue text.