code: function Flyout_checkKeyboardFit() {
                      // Special Flyout positioning rules to determine if the Flyout needs to adjust its
                      // position because of the IHM. If the Flyout needs to adjust for the IHM, it will reposition
                      // itself to be pinned to either the top or bottom edge of the visual viewport.
                      // - Too Tall, above top, or below bottom.
  
                      var keyboardMovedUs = false;
                      var viewportHeight = _Overlay._Overlay._keyboardInfo._visibleDocHeight;
                      var adjustedMarginBoxHeight = this._currentPosition.contentHeight + this._currentPosition.verticalMarginBorderPadding;
                      if (adjustedMarginBoxHeight > viewportHeight) {
                          // The Flyout is now too tall to fit in the viewport, pin to top and adjust height.
                          keyboardMovedUs = true;
                          this._currentPosition.top = _Constants.pinToBottomEdge;
                          this._currentPosition.contentHeight = viewportHeight - this._currentPosition.verticalMarginBorderPadding;
                          this._currentPosition.doesScroll = true;
                      } else if (this._currentPosition.top >= 0 &&
                          this._currentPosition.top + adjustedMarginBoxHeight > _Overlay._Overlay._keyboardInfo._visibleDocBottom) {
                          // Flyout clips the bottom of the viewport. Pin to bottom.
                          this._currentPosition.top = _Constants.pinToBottomEdge;
                          keyboardMovedUs = true;
                      } else if (this._currentPosition.top === _Constants.pinToBottomEdge) {
                          // We were already pinned to the bottom, so our position on screen will change
                          keyboardMovedUs = true;
                      }
  
                      // Signals use of basic fadein animation
                      this._keyboardMovedUs = keyboardMovedUs;
                  }
docs: If you were not pinned to the bottom, you might have to be now.