Option-Dragging Back to Default Formatting
Last Saturday, I witnessed a UFO. No, not the things from Area 51 and/or outer space. I mean an InDesign UFO, an Unexpectedly Formatted Object. Specifically, I stumbled on a weird phenomenon regarding object formatting and the Direct Selection tool. Under certain circumstances, if you attempt to duplicate an object by Option-dragging it with the Direct Selection tool, the formatting of the new object changes to match the default formatting for that type of object in the document.
If you Option drag lines, open paths, rectangles, ellipses, and polygons, the new object will take on the stroke, fill, corner options, effects, opacity, and object style that you see in the Control panel with nothing selected.
If you Option drag a frame containing a placed graphic (not the graphic itself), or an object made with any of the 'Frame' tools (Rectangle Frame Tool, Ellipse Frame Tool, Polgyon Frame Tool), the new copy will have the default fromatting for those objects, which is no formatting: no stroke, no fill, etc.
As I mentioned above, the default formatting doesn't always happen when you Option-drag. You can usually tell what will happen by your cursor when you mouse over an object. If you Option-drag when your cursor is a white arrow with a line, the new object will have default formatting. If you Option-drag when your cursor is a white arrow with a point, the new copy will have the same formatting as the original object.
To illustrate the phenomenon, try this test for yourself. Draw a rectangle and give it some interesting formatting.
Then deselect everything (Command-Shift-a). Now go to the Control panel and change the document's defaults to something else very different from your rectangle's formatting.
With the Direct Selection tool, click in the very center of the rectangle, so the control point is filled in.
Hold Option and drag the center point. Voila, the copy has default formatting.
If you Option-drag just a segment of the rectangle, then it will be duplicated and have the default formatting.
I don't know if this is a Mac-only issue, or if the same things happen when you Alt-drag on the PC. Also, while it was news to me, this has been around for a while. I get the same results with CS3, 4, and 5. Makes me wonder what else has been lurking under my cursor all these years. Keep watching the skies, er, screens.