When we discussed drag and drop in Chapter 2 we stressed the challenge of getting the interaction right. There are more than a dozen interesting moments of interaction in any drag and drop interaction (see Figure 2-2). Many of these moments are opportunities to provide Drag and Drop Invitations.
In Chapter 2, we listed 15 different events that are available to the designer to cue the user during a drag and drop interaction. Here are the 15 drag and drop events we listed in that chapter:
Drag Leaves Original Location
Drag Re-Enters Original Location
Drag Enters Valid Target
Drag Exits Valid Target
Drag Enters Specific Invalid Target
Drag Is Over No Specific Target
Drag Hovers Over Valid Target
Drag Hovers Over Invalid Target
Drop on Parent Container
As with any complex interaction, it is key to guide the user through each step. Given this many interactions, it's important to show invitations at key moments.
While at Yahoo!, I (Bill) worked on the Yahoo! for Teachers product. A key feature is the Yahoo! Gobbler™, which allows teachers to grab text clippings, images, and links from pages around the Web and "gobble" them back to their classroom projects (Figure 10-10).
Figure 10-10. Yahoo! for Teachers ...