This is a bit difficult to explain, so if it's not clear, let me know.
First part: The flashing button color 'bleeds' off the right side of the button. See image #1.
* It only shows when you have 2 messenger windows open at the same time and one flashes.It does not show when there is only one open.
* It only shows when you have the text hidden on the buttons.
* It does not show on all Windowblinds, I'm using Corporate as an example but I've seen it on other blinds too.
* The flashing button image is exactly the same size as the regular taskbar buttons. All margins are exactly the same.
Second part: The flashing button changes size. See image #2.
Same button, but with the text showing now, and the buttons are not stacked.See the distance the flashing button is from the others?
* The left side of the button shifts one pixel to the left when the flashing button appears, the right side remains where it is.
* Once the button has flashed, and you activate the window, the button remains shifted until you close the window.
A few other blinds that do this are: Dulce, Precision, Trident, Blue OS, Cinnabar