If an action choice can possibly refer to more than one control in a
window, use the following rules to determine which control is affected:
If the action can be applied to the control that has focus emphasis, apply
it to that control.
For example, if the focus is in a text-entry field and the user uses a
shortcut key to invoke the Paste choice, paste to the text-entry field that
has focus.
If the action operates on a selection, apply the action to the primary
selection when the following is true:
The primary selection is in the window
No editing operation has been done in any other control in the window
since it was selected
If the control with interacted emphasis is in the window and the action
can be applied to it, apply it.
The control with interacted emphasis is the last editable control the user
interacted with, so, for example, if the user last interacted with a
text-entry field, paste to that field.
If the window has a main control and the action can be applied to it,
apply it.
For example, a drawing program might have a large drawing area and a small
text-entry field for entering identification numbers. The drawing area is the
main control; if the previous cases do not apply, paste to it.
If none of the previous cases is true, then invoking the action has no
effect except for invoking a warning message.