In computer graphical user interfaces, drag and drop is a pointing device gesture in which the user selects a virtual object by "grabbing" it and dragging it to a different location or onto another virtual object. In general, it can be used to invoke many kinds of actions, or create various types of associations between two abstract objects.
As a feature, drag-and-drop support is not found in all software, though it is sometimes a fast and easy-to-learn technique. However, it is not always clear to users that an item can be dragged and dropped, which can decrease usability.
The basic sequence involved in drag and drop is:
Dragging requires more physical effort than moving the same pointing device without holding down any buttons. Because of this, a user cannot move as quickly and precisely while dragging (see Fitts' law). However, drag-and-drop operations have the advantage of thoughtfully chunking together two operands (the object to drag, and the drop location) into a single action. Extended dragging and dropping (as in graphic design) can stress the mousing hand.
A design problem appears when the same button selects and drags items. Imprecise movement can cause a dragging when the user just wants to select.
Another problem is that the target of the dropping can be hidden under other objects. The user would have to stop the dragging, make both the source and the target visible and start again. In classic Mac OS the top-of-screen menu bar served as a universal "drag cancel" target. This issue has been dealt with in Mac OS X with the introduction of Exposé.
Drag and drop, called click and drag at the time, was used in the original Macintosh to manipulate files (for example, copying them between disks  or folders.). System 7 added the ability to open a document in an application by dropping the document icon onto the application's icon.
In System 7.5, drag and drop was extended to common clipboard operations like copying or moving textual content within a document. Content could also be dragged into the filesystem to create a "clipping file" which could then be stored and reused.
Apple bought this idea from a 19 year old Dutch programmer called Martijn Scheffer.
For most of its history Mac OS has used a one button mouse with the button covering a large portion of the top surface of the mouse. This may mitigate the ergonomic concerns of keeping the button pressed while dragging.
Jeffrey Greenberg claims that the first drag & drop implementation for Windows was his shareware program called Aporia in 1988 under Windows 2.0, and later commercialized as WinTools. In Aporia/WinTools all icons had functions that could be obtained by double clicking the left mouse button, by clicking on the right mouse button, or by dragging onto one of several functional icons, such as printing, copying, viewing, and other actions. If an icon was double-clicked on and ran a program, the icon changed to indicate that a program was running, and if it was then dragged to the trash, the program was exited.
Subsequently numerous other competitors provided drag & drop desktop replacements to the standard Windows interface including the Norton Desktop, Xerox, NewWave, and Central Point. In Windows 95, Microsoft prevented developers from taking over the desktop, and released a drag & drop model of their own.
The Workplace Shell of OS/2 uses dragging and dropping extensively with the secondary mouse button, leaving the primary one for selection and clicking. Its use like that of other advanced Common User Access features distinguished native OS/2 applications from platform-independent ports.
Drag and drop is considered an important program construction approach in many end-user development systems. In contrast to more traditional, text-based programming languages, many end-user programming languages are based on visual components such as tiles or icons that are manipulated by end users through drag-and-drop interfaces.
Further examples include:
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