Dock Docking position: horizontal/vertical. Defines a position on the element which is used for aligned positioning of another element (e.g. the left top corner of a popup is positioned at the left bottom corner of the input field). For the horizontal position possible values are "begin", "left", "center", "right" and "end", where left/right always are left and right, or begin/end which are dependent on the text direction. For the vertical position possible values are "top", "center" and "bottom". Examples: "left top", "end bottom", "center center". (begin|left|center|right|end) (top|center|bottom)