December 2004 | Page 4 of 4 | The Old New Thing

Dragging a shell object, part 1: Getting the IDataObject

Raymond Chen December 6, 2004 Dec 6, 2004 12/6/04

The shell gives you the IDataObject; all you have to do is drag it around. (This is the first of a five-part series.) Start with the scratch program, and add the function GetUIObjectOfFile from an earlier article. Also, change the calls to CoInitialize and CoUninitialize to OleInitialize and OleUninitialize, respectively, since we're...

Why are documents printed out of order when you multiselect and choose “Print”?

Raymond Chen December 3, 2004 Dec 3, 2004 12/3/04

If you select say five files and then right-click them and choose "Print", they tend to print in a random order. Why is that? The shell invokes the Print verb on each file in turn, and depending on how the program responsible for printing the document is registered, one of several things can happen. These three ways of registering ...

Why did Windows 95 run the timer at 55ms?

Raymond Chen December 2, 2004 Dec 2, 2004 12/2/04

The story behind the 55ms timer tick rate goes all the way back to the original IBM PC BIOS. The original IBM PC used a 1.19MHz crystal, and 65536 cycles at 1.19MHz equals approximately 55ms. (More accurately, it was more like 1.19318MHz and 54.92ms.) But that just pushes the question to another level. Why 1.19...MHz, then? With that ...

What is the purpose of the bmPlanes member of the BITMAP structure?

Raymond Chen December 1, 2004 Dec 1, 2004 12/1/04

Many bitmap-related structures in Windows have a field called "planes". For example the BITMAPINFOHEADER structure has a biPlanes member (which must be set to 1). The BITMAP structure has a field called bmPlanes. What's the deal with that field? The EGA video adapter supported 16 simultaneous colors. This was an enormous improvement over ...

The Old New Thing

December 2004 | Page 4 of 4 | The Old New Thing

Dragging a shell object, part 1: Getting the IDataObject

Why are documents printed out of order when you multiselect and choose “Print”?

Why did Windows 95 run the timer at 55ms?

What is the purpose of the bmPlanes member of the BITMAP structure?

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