When editing an input field, even in something as simple as an Expression element, I run into confusing editing behavior.
For example, let's say that I have copied an Expression to make another similar one. I enter the input field, and select some text for replacement. It works as expected, and the replacement text, either typed or pasted with ^V, replaces the selected text. So far so good. Then I select another bit of text for replacement in the same input field. On any try after the first one, the selected text does not get replaced, it gets added to. The workaround is to select the text, explicitly delete it, and then add (by typing or pasting) the replacement text. This behavior is inconsistent with Windows standards, and indeed within just the input field.