Drag-and-Drop Transfer

Support dragging any object represented as an icon.

Support dropping onto objects represented as icons.

If a control supports any form of data transfer with its contents used as a source, then those contents can be the source of a drag-and-drop operation.

If a control allows any form of data transfer to the control, it can be used as a target for a drag-and-drop operation.

Make the source of a drag-and-drop transfer the element or selection on which the drag was initiated.

Make the target of a drag-and-drop transfer the control on which the drop was performed; if the control holds a selection scope, then it is the insertion point within that scope.

The default operation for a drag-and-drop transfer must be a move, except in the following cases:

The default operation for a drag-and-drop transfer may be overridden by Ctrl and/or Shift modifiers when the TRANSFER button is released.

Allow users to control whether nonselectable elements such as labels can be dragged or not.

Make any basic function available through a drag-and-drop transfer also available through predefined shortcut keys, menus, push buttons, or secondary windows. That is, provide drag-and-drop transfer as a shortcut to functions that are accessible through other interface controls supported within your application. Do not provide any basic operation that is supported solely through a drag-and-drop transfer.

Initiate a drag when the user presses the TRANSFER button and then moves the mouse on selections and elements that can be dragged.

If the user uses the TRANSFER button to drag an element that has not been selected, drag only that element without affecting any existing selection.

Drag all selected elements in the scope when the user presses the SELECT button and then moves the mouse on a selection.

Initiate a drag when the user clicks Alt TRANSFER on a selection or an element that can be dragged.

Whether the TRANSFER button is integrated with SELECT on MB1 or not, when the user clicks SELECT, optionally augmented with Shift and/or Ctrl, the effect should be the same.

When the user multi-clicks (or multi-presses) the SELECT button, optionally augmented with Shift Ctrl, the effect should be the same whether the TRANSFER button is integrated with SELECT on MB1 or not.

When the user presses MB1 and moves the pointer on a selection, drag all selected elements in the scope.

When the user presses MB1 on an element that can be activated or toggled (other than a tear-off choice), activate or toggle the element; do not allow dragging.

When the user presses MB1 and moves the pointer on an element that cannot be selected (other than a tear-off choice), do not allow dragging.

If the MENU button is bound to a mouse button other than MB1, when the user clicks Alt MB1, optionally augmented with Shift and/or Ctrl, on a selection or an element that can be dragged, initiate a drag.

Whether the TRANSFER button is integrated with SELECT on MB1 or not, support the same effect when the user presses SELECT and moves the pointer, optionally augmented with Shift and/or Ctrl, in the background (or on unselected text) of a scope that supports area or range selection techniques.

When the TRANSFER button is integrated with SELECT on MB1 in a nontextual scope that supports neither area nor range selection techniques, pressing MB1 and moving the pointer, optionally augmented with Shift and/or Ctrl, in the background can be used either for dragging the entire selection scope or for panning.

When the TRANSFER button is integrated with SELECT on MB1, when the user presses MB1 and moves the pointer, optionally augmented with Shift and/or Ctrl, on an unselected element for dragging, the effect should be equivalent to the user clicking the SELECT button (without modifiers) on the element (using whatever selection model is in force) and then dragging the selection.

When the TRANSFER button is integrated with SELECT on MB1 in a nontextual scope, treat pressing MB1 and moving on an unselected element as a selection technique if the following is true:

Otherwise, allow the user to press MB1 and move the pointer on an unselected element for dragging.

When the TRANSFER button is integrated with SELECT on MB1, then treat pressing Shift MB1 and moving the pointer on an unselected element as a selection technique only if adjustment selection techniques can be used in the scope and if the scope is densely populated. Otherwise, allow pressing Shift MB1 and moving the pointer for dragging.

When the TRANSFER button is integrated with SELECT on MB1, treat pressing Ctrl MB1 and moving the pointer on an unselected element as a selection technique only if group selection techniques can be used in the scope, if Ctrl forces use of toggle mode instead of select mode, and if the scope is densely populated. Otherwise, allow pressing Ctrl MB1 and moving the pointer for dragging.

When the TRANSFER button is integrated with SELECT on MB1, allow the user to press Ctrl Shift MB1 and move the pointer on an unselected element for dragging.

If the drag pointer's source indicator consists of a graphic image of the source and if the operation is a move, hide the source, especially if the operation indicator is used.

When a user pauses on an icon (for a time that the user can set) during a drag-and-drop operation, display and raise the window used to view the corresponding object.

The application that contains the source elements of a drag-and-drop operation may limit drops to windows that it manages. It may also treat elements of its own or other applications as invisible for the purpose of determining the target.

When a drag is completed, a drop should be performed at the pointer location as follows:

In any case, the state of the Ctrl and Shift modifiers at the time of the drops determines the operation to be performed.

When a drag is in progress and the user presses Cancel, cancel the drag.

When a drag is in progress and the user presses Help, post a Help dialog that describes the result of a drop at the pointer location. The Help dialog should allow the drop to be performed (if it would likely succeed) or canceled (via a Cancel choice) or additional Help to be obtained (via a Help choice).

If different operations can be performed as a result of a drop (for example move, copy, or link), provide push buttons labeled with all the choices in the Help dialog.

The Help dialog can contain a Resume choice if the drag can be resumed.

When the user attempts to drop an element on an element that does not support the operation, cancel the drag or display a message dialog similar to the one that would be used if Help were pressed at that location.

When a user drops a source element onto the same position it currently occupies, the application should not perform an action.

If the source elements of a drag-and-drop move operation are selected, select the elements transferred to the target scope if the source and target scopes are the same.

If the source elements of a drag-and-drop move operation are selected, select the elements transferred to the target scope if the target uses normal mode and allows the number of elements transferred to be selected.

Move focus to the target control in a drag-and-drop operation.

If the user drops an element at an inappropriate drop site, design your application to display a "snap back" effect and to display an error message indicating the reason the drop was not allowed. Within the error message, state the context of the error (for example, trying to perform action A on object B), what happened (for example, could not connect to system X), and how to correct the problem (for example, direct the user to press the Help push button for information).

When the user selects the target of a drag-and-drop link operation, make a link (in an application-specific manner) from the selected elements to the source elements.