## Issue
When navigating back and forth between a File and Channel page, the back-action will be laggy (no response) if the channel contains a lot of comments and is in the midst of resolving them.
## Changes
The "full" fix would be to batch-load comments, as this would improve the performance of fetching both Channel and File comments. For now, this commit focuses on the Back action problem only.
Skip fetching comments by not mounting 'ChannelDiscussion' until the tab is selected. I couldn't find anything in the Reach UI documentation on how to not render inactive `TabPanel`s, so I used the straight-forward state method.
## Issue:
Fixes 4411 `"SelectChannel=New" doesn't show all fields on re-entry`
## Code Changes:
`selectChannel`: Correct the value of `addingChannel` in the constructor based on the given props.
(1) This reverts commit 8641a3ee1c.
(2) Fix floating-player misalignment due to YT badge in mobile by hiding the badge.
At first, the suggestion to truncate the left URI to keep the entire thing single-lined was implemented, but during testing, I realized that the YT badge will take up the entire width anyway (especially on other languages). The URI is more important than the badge, and truncating both of them would be ugly.
Given the preference to not have 2 lines for this, we'll just hide the badge for the mobile case.
For the Channel Page case, let's make it single-line through "4454: URL / top claims overlap" instead. We'll keep this commit/PR limited to fixing the YT badge.
## Issue
Fixes 4524 `[mobile] in channel search not available`
## Changes
There are currently 3 wunderbars: (1) header (2) channel list (3) downloaded list.
The additional `wrapperStyle` in the header made it hard to find a solution that works for all 3, so I split 2 and 3 into `wunderbar__input--inline`.
## Issue:
Currently, the checkbox grayed-out state is only correctly updated when changing from "no-file" to "file selected". If you have selected a video file and later changed to a text file, the checkbox doesn't gray out.
## Code Changes:
`fileVid` wasn't being updated for the case of non-videos; now it does.
## Issue
Closes 3964 `Add Youtuber info to file page`
## Changes
(1) Refactor the YT-info query into `YoutubeBadge` component.
(2) For the File Page case, don't show "- last sync <date>" since the date has nothing to do with the file.
## Test
[x] YT Channel page
[x] YT Channel's claim page
[x] Non YT Channel page
[x] Non YT Channel's claim page
[x] No channel (anonymous) claim page
[x] Various RENDER_MODES
