Non-functional usability checklist

This checklist is dedicated to simple, small, and mostly non-functional features, that are considered as default and expected behavior of application UI and its elements. Most of it is available in native UI-frameworks of operational systems like Windows and macOS, but because of multiple reasons, web frameworks and applications quite often miss some of the features, that reduce usability of the products.

1. Hover and pressed states of controls (like buttons) differ.
2. Pressed state of non-activated toggle button differs from “activated” normal state and vice versa.
3. All text that doesn’t fit the container is truncated with ellipses and is shown by tooltip when the user hovers the cursor over it.
4. Any popup or dropdown list can be hidden by pressing ESC button.
5. If the dialog window is shown, pressing ESC keyboard button acts similar to the click on the Close or Cancel buttons of the dialog.
6. If the dialog window is shown, pressing Enter keyboard button acts similar to the click on the default button (that typically confirms the entry or changes in the dialog window).
7. There is only one default (primary or emphasized) button in the window (main window of the application, or dialog window).
8. Most UI controls may get keyboard focus to be controlled from keyboard. For instance, sliders, checkboxes, knobs, etc.