The channel this kind of display is handed over on
This frame's connection
The longest the holder takes to close the device, which is how long an ask waits once it is told the device is closing
Asks whichever other frame on the page holds the display to let it go, and waits until it has.
Resolves at once where no frame holds the display, or where the browser has no way to ask.
The frame that let the display go, to be given it back should opening it here fail, or null when no frame held it
Gives the display back to the frame that let it go, when opening it here failed.
The ask closed a connection that was working. A frame that then cannot open the device -- a Bluetooth link that drops as it reconnects, a display switched off a moment ago -- would otherwise leave the reader with no display anywhere, for a failure that had nothing to do with the chart that had it.
The frame that let it go, or null when none did
Passes a tactile display between the frames of one page.
A device can be open in one frame at a time, and in a notebook or a rendered document every chart is a frame of its own. A connection the reader made in one chart was kept there for as long as that frame lived, so every other chart found the device busy and the reader had to connect again in each one. Asking is what lets the connection follow the reader from chart to chart until they disconnect it themselves.
Each kind of display has a channel of its own, so asking for one never makes a frame give up a different device.