The parameters described below provide support for resizing a frame by dragging its internal borders with the mouse. They also allow moving a frame with the mouse by dragging the header or tab line of its topmost or the mode line of its bottommost window.
These parameters are mostly useful for child frames (see Child Frames) that come without window manager decorations. If necessary, they can be used for undecorated top-level frames as well.
drag-internal-border
If non-nil
, the frame can be resized by dragging its internal
borders, if present, with the mouse.
drag-with-header-line
If non-nil
, the frame can be moved with the mouse by dragging the
header line of its topmost window.
drag-with-tab-line
If non-nil
, the frame can be moved with the mouse by dragging the
tab line of its topmost window.
drag-with-mode-line
If non-nil
, the frame can be moved with the mouse by dragging the
mode line of its bottommost window. Note that such a frame is not
allowed to have its own minibuffer window.
snap-width
A frame that is moved with the mouse will “snap” at the border(s) of the display or its parent frame whenever it is dragged as near to such an edge as the number of pixels specified by this parameter.
top-visible
If this parameter is a number, the top edge of the frame never appears
above the top edge of its display or parent frame. Moreover, as many
pixels of the frame as specified by that number will remain visible when
the frame is moved against any of the remaining edges of its display or
parent frame. Setting this parameter is useful to guard against
dragging a child frame with a non-nil
drag-with-header-line
parameter completely out of the area
of its parent frame.
bottom-visible
If this parameter is a number, the bottom edge of the frame never
appears below the bottom edge of its display or parent frame. Moreover,
as many pixels of the frame as specified by that number will remain
visible when the frame is moved against any of the remaining edges of
its display or parent frame. Setting this parameter is useful to guard
against dragging a child frame with a non-nil
drag-with-mode-line
parameter completely out of the area of
its parent frame.