Discovered while testing on desktop. When the button is being pressed, or mouse hovering, ui-btn-hover-* or ui-btn-down-* would be applied on the button. At such case, those classes would not be removed by .buttonMarkup().
Also included workaround for #3635.
Included in #3635
[buttonMarkup] Track addition/removal of up/down/hover classes to rec…
…onstruct button state during re-enhancement -- Fixes #3637