How to read the button test
Press each button inside the test surface. A row changes while the button is held and its count advances on press. The test uses the browser button numbers defined for primary, auxiliary, secondary, Back, and Forward input.
Why Back and Forward may not appear
Some browsers, operating systems, extensions, and mouse utilities reserve navigation buttons before a page receives them. The test reports Detected only after an actual button 3 or 4 event arrives; it never invents support from the device name.
Right-click behavior stays contained
The context menu is prevented only over the test surface so a right-button press can be counted. Right-clicking the navigation, article text, or any other part of the site keeps normal browser behavior.
Use each focused test to compare click, button, wheel, and movement behavior without uploading event data.