Text cursors can exist in multiple fields

The bug

When you simply click on input boxes in a certain order, the typing cursor shows for all the boxes. However, what you type will only go in the last box that you clicked.

Note: I get the impression that this happens when you first select a box "below" the next one.

How to reproduce

1. Go to a place where there is more than one input box (for example in a structure block or in the "add multiplayer server" menu)
2. Click on all the input boxes in several different orders

Examples

Here are some examples in videos:

• You can select multiple input boxes at the same time (1).mp4
• You can select multiple input boxes at the same time (2).mp4

Bug additions (Thanks Matolcsy Attila)

• The bug is only visual, you can still only edit one box a time
• Bug only appears when using mouse clicks, not while using Shift+Tab
• Bug only appears if Server Adress is selected first, not the other way

Code Analysis provided by haykam found in this comment