Zoom on double click over keys

[jorgemota]

I am testing this keyboard, but if user clicks quickly on keys (double, triple tap ) on touch devices, the page is zoomed, I already added to my page the viewport
meta name="viewport" content="width=device-width; initial-scale=1.0; maximum-scale=1.0; user-scalable=0;"

tried with
meta name="viewport" content="width=device-width; initial-scale=1.0; maximum-scale=1.0; user-scalable=no;"

Added code to touchend and touchstart event of elements for virtualkeyboard keys but I can't stop the zoom on touch events :( the same thing happens on http://the-darc.github.io/angular-virtual-keyboard/ using a touch device.