Q When my application calls the Drag Manager's TrackDrag and the user drags text out of my application onto the desktop, a clipping file appears. Or at least it does under System 7.5; under System 7.1, nothing happens. Why?
A In Systems 7.1 through 7.1.2, Drag Manager is
implemented by means of multiple extensions (all in the Extensions
folder), and various pieces of functionality appear according to
which extensions are installed. You cannot count on any of these
extensions being installed, so if you want your application to use
the full functionality of Drag Manager under these system versions,
you'll want your app's installer to install these extensions.
Some systems may already have older versions of Drag Manager components, in which case you may want to replace them with newer versions. If you do, be sure to install all of the appropriate files to ensure version parity on the user's system.
The following chart describes which components implement which functionality on which system. It is provided only for purposes of installation. Your application should not attempt to determine what functionality is available according to which files are installed (since users may only have enabled some extensions without restarting, and since different versions of the system require different sets of extensions). Your application should instead test for Drag Manager functionality only via the gestaltDragMgrAttr Gestalt selector.
|
Feature |
System 7.1 |
System 7 Pro (System 7.1.1) |
System 7.1.2 (Power Macs) |
|
Intra-application drag and drop |
Macintosh Drag and Drop |
Macintosh Drag and Drop |
Macintosh Drag and Drop |
|
Inter-application drag and drop |
Macintosh Drag and Drop, Dragging Enabler |
Macintosh Drag and Drop |
Macintosh Drag and Drop |
|
Drag and drop to and from Finder |
Macintosh Drag and Drop, Dragging Enabler, Finder 7.1.3 |
Macintosh Drag and Drop, Dragging Enabler |
Macintosh Drag and Drop, Dragging Enabler, Finder 7.1.3 |
|
Clippings |
Macintosh Drag and Drop, Dragging Enabler, Finder 7.1.3, Clipping Extension |
Macintosh Drag and Drop, Clipping Extension |
Macintosh Drag and Drop, Dragging Enabler, Finder 7.1.3, Clipping Extension |
(You should not install Finder 7.1.3 on user systems; in fact, there is not an easily available license for shipping it. However, before System 7.5 it was the only way for developers without System 7 Pro, which has Finder 7.1.3, to debug their code, so its use is documented here for historical reasons.)
Under System 7 and 7.0.1, Drag Manager is supported, but only for intra-application dragging. This makes it less desirable to install the required Macintosh Drag and Drop extension, because it provides nothing which cannot be implemented via judicious use of QuickDraw, Window Manager, and OSEventAvail.
Under System 7.5, the picture is equally simple but significantly richer. All Drag Manager functionality is built into or installed with the system.
-- Pete Gontier
Worldwide Developer Technical Support
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