Consider implementing isAccessibilitySelectorAllowed

Some properties that are exposed through QMacAccessibilityElement are only relevant for certain element types/roles, but they are exposed regardless. You can see this by using Accessibility Inspector on a QSlider vs using it on a macOS slider and compare the difference. Attached is the screenshot of Accessibility Inspector for Screenshot macOS Slider.png and Screenshot QSlider.png . (Notice that QSlider has some cruft that only makes sense to text elements). Currently, the properties that are affected by this is:

• accessibilityNumberOfCharacters
• accessibilityVisibleCharacterRange
• accessibilityInsertionPointLineNumber
• accessibilitySelectedText
• accessibilitySelectedTextRange

This list will expand as we implement more specialized behavior (e.g. the table type will probably need to implement accessibilityRows, accessibilityColumns and accessibilityIndex, which are irrelevant for e.g. a slider).

It turns out that this can be controlled by implementing

isAccessibilitySelectorAllowed

For reference, this is a simple implementation on how a basic implementation can be:

- (BOOL)isAccessibilitySelectorAllowed:(SEL)selector {
    QAccessibleInterface *iface = QAccessible::accessibleInterface(axid);
    if (iface && iface->isValid()) {
        if (!iface->textInterface()
                && (selector == @selector(accessibilityNumberOfCharacters)
                || selector == @selector(accessibilityVisibleCharacterRange)
                || selector == @selector(accessibilityInsertionPointLineNumber)
                || selector == @selector(accessibilitySelectedText)
                || selector == @selector(accessibilitySelectedTextRange))) {
            return false;
        }
    }
    return true;
}