The blinking text cursor doesn't disappear when the textbox is deselected in a structure block

Bug

When a textbox is selected in a structure block, a caret (flashing underscore symbol) appears, which is normal. When I select a different textbox, however, the caret doesn't disappear from the first textbox and a caret appears in the second one. I am able to do this indefinitely- or at least until there aren't any textboxes left. Also, sometimes selecting a textbox removes one or multiple other carets seemingly at random.

Expected Result

The only caret that exists at one time is in the selected textbox.

Actual Result

Multiple carets appear at the same time in different textboxes.

Steps to Reproduce

1. Place down a structure block
2. Open the block's GUI
3. Go to "Save" or "Load" mode
4. Start clicking on textboxes
5. You will eventually see multiple text cursors