Opera Bug #DSK-372334

In-progress CSS opacity transitions are not cancelled when reverted in a separate JavaScript thread

Affects up to Opera 12.15

Fail if the green square fades to red on page load, or when the button is clicked.

The green square above has a CSS opacity transition applied, and overlaps a hidden red square.

On page load, and when the button is clicked, the CSS opacity property of the green square is changed to 0. This is immediately followed by a zero-second setTimeout which sets the opacity property back to 1. Expected effect is that Opera should recognise the transition in progress and reverse it immediately, effectively cancelling the transition almost before it starts. Visually, nothing should appear to be animating/transitioning.

Opera sees the initial fade-out transition to its conclusion, and then abruptly reverts the opacity back to 1 without any transition. It appears as though some portion of these transitions are being queued improperly.

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