Oh sorry. To be explicit, if you select the text and it disappears, it is still selected, just not visible. So you can still copy the text with Ctrl - C (even though it isn't visible) and paste into Notepad or whatever else with Ctrl - V.
When you want to import the string, paste it in and hit the Checkmark Button to import. If you click the string, the UI may disappear if it gets selected, but click it again to deselect the text and it should come back.