"Ghost headers" in certain tabs

In some tabs (specifically, Next Match and Data Spitter), the headers for the table will appear once you select an event but disappear after a short time.

To reproduce this, start the app and quickly switch to the "Next Match" tab (or "Data Spitter") and select an event code. The headers for the table of data will pop up but disappear after a few seconds.

The expected response is that no headers should be shown unless both an event code and a next match number/team to data spit are selected, i.e. only when there's actual data to show alongside the headers.

Because this only works if you do it quickly after startup and disappears after a few seconds might mean it's something to do with the `refresh()` function that updates stuff every once in a while. I also wonder what the criteria is for showing the headers of the table?

(Try and fix this on a new branch. There might be multiple ways of solving this, just pick one that works. If you just can't solve this after giving it a day or two, you can ask me for more hints)

Start the app and reproduce the issue in the Next Match and Data Spitter tabs by selecting an event code immediately after startup. Inspect the refresh() logic and the criteria controlling table headers; done means headers appear only when an event code and the required match number or team are selected.

Written by the indexing model from the issue text.