Using Copy as the Default Drag-and-Drop Verb

The available drag-and-drop operations are determined by the enabled state of the Copy and Cut verbs, as shown in the following table.

Copy	Cut	Available operations
Enabled	Enabled	Copy, Move
Enabled	Disabled	Copy
Disabled	Enabled	Move
Disabled	Disabled	None

 

When both Copy and Move are available (as is the case when the Copy and Cut verbs are enabled), the snap-in has the ability to specify whether Move or Copy is the default operation. (Be aware that in MMC 1.2, Move, or "Move Here", was the default operation, and it was not modifiable). The default operation is executed when no keys are pressed while the user performs a left-button drag-and-drop operation; the default operation also appears as a bold context menu item when the user is prompted after performing a right-button drag-and-drop operation. If your snap-in wants Move ("Move Here") as the default operation, no action must be taken. If your snap-in wants Copy ("Copy Here") as the default operation, specify the MMC_DEFAULT_OPERATION_COPY flag when responding to the MMCN_QUERY_PASTE notification; the snap-in can specify this flag using the pointer to the DWORD value passed as the MMCN_QUERY_PASTE's param parameter.

If the user presses the CONTROL or SHIFT key during left-button drag-and-drop operation, the use of MMC_DEFAULT_OPERATION_COPY has no effect. The following depicts the left-button drag-and-drop operation based on the user's choice of keys (if any) and the snap-in's use of MMC_DEFAULT_OPERATION_COPY in response to MMCN_QUERY_PASTE. Assume that both Cut and Copy are enabled.

Key pressed	MMC_DEFAULT_OPERATION_COPY not set	MMC_DEFAULT_OPERATION_COPY set
(None)	"Move Here"	"Copy Here"
Control	"Copy Here"	"Copy Here"
Shift	"Move Here"	"Move Here"