CheckedScriptFileInputBox should run type checking when user returns to the tab

A common workflow is to open an extension point, eg a script field that has a linked script in an external file.

You make changes in this file, either in the script editor or another file editor.

When you then return to the script field, you want to make sure that type checking shows no errors. There's no good way to do this, a workaround is to add a space after the file name.

It would be better if STC automatically re-ran when you return to that browser tab.