Right...

Here's the explanation, bit tricky...

To emulate, find a string input field... for instance the object name input in the properties panel. Now enter a really long name, for instance abcdefghijklmn

Now make the properties panel so narrow that you can no longer see the entire name in the input.

It shows you the "end" of the string, not the start... I'd prefer seeing the start, but that's "design".

Now... go edit the name... move the cursor all the way to the front of the name... and add a letter there... so the name for instance becomes: Zabcdefghijklmn

It then has the cursor behind the Z and moves the text in the input so that the cursor is at the start of the input, and you can't see the Z. This is rather annoying, you're tempted to think your added letter was not added.

I'd suggest, show the start of the string by default... and if the cursor is placed so many letters from the left that it goes beyond the "middle" of the input field... try placing the string in the field so that the cursor is in the middle. Unless there's less than half of the input size left (behind the cursor), then just move the cursor to the right of in the input (keeping all of the end of the text in view).

I hope this makes sense.