Is it possible to kick start keyboard dismiss interactively operation (Like WhatsApp) before the drag down operation touching the keyboard?

[yccheok]

Currently, the keyboard only start kick start keyboard dismiss interactively operation when drag down operation touching keyboard edge.

However, in WhatsApp app, the keyboard dismiss operation will kick start, when the drag operation touches the bottom bar edge, even before touching keyboard edge.

Does anyone have idea what is the technique used by WhatsApp, to achieve such behavior? Thanks.