The exception is when you are editing text in an object. In that case, Delete deletes forward and Backspace deletes backward. The Alt key is a very useful accelerator. Type Alt plus the underlined letter in a window button to activate that button. For example, see the buttons in the dialog below.
Most text fields have a white background.
Such text fields are editable. Text fields with a gray background are not editable. In Visual Thought, sliders always have numeric fields above them. You can move the slider or enter an exact value, whichever you want to do. File Choosers Double-click on a filename or a directory to open it.