The Old New Thing

Dragging a shell object, part 4: Adding a prettier drag icon

December 9, 2004 Dec 9, 2004 12/9/04

Raymond Chen

You may have noticed that the drag feedback is rather sad-looking. Just a box, maybe with a plus sign or an arrow; you don't even know what it is you're dragging. Let's fix that. We'll drag the icon of the file around. We'll need to add the drag image to the data object. void OnLButtonDown(HWND hwnd, BOOL fDoubleClick, int x, int y, UINT...

Dragging a shell object, part 3: Detecting an optimized move

December 8, 2004 Dec 8, 2004 12/8/04

Raymond Chen

We were considering how to detect that the drag/drop operation resulted in a conceptual Move even if the DROPEFFECT_MOVE was optimized away. If the drop target is the shell, you can query the data object for CFSTR_PERFORMEDDROPEFFECT to see what the performed effect was. void OnLButtonDown(HWND hwnd, BOOL fDoubleClick, ...

It is not illegal to use James Bond style tactics for winning at the roulette wheel

December 8, 2004 Dec 8, 2004 12/8/04

Raymond Chen

In an operation straight out of a James Bond movie, a trio of gamblers used a laser range-finder hidden in a mobile phone to predict the likeliest landing spot of a roulette ball, reducing the odds from 37-1 to 6-1. Scotland Yard concluded that they did nothing illegal and were allowed to keep their winnings. I wonder how long it'll be ...

Researchers find connection between lack of sleep and weight gain

December 7, 2004 Dec 7, 2004 12/7/04

Raymond Chen

Shortage of sleep is linked to obesity , according to research published yesterday. Lack of sleep boosts levels of a hormone that triggers appetite and lowers levels of a hormone that tells your body it is full according to the team. The scientists will now study whether obese people should sleep more to lose weight...

Dragging a shell object, part 2: Enabling the Move operation

December 7, 2004 Dec 7, 2004 12/7/04

Raymond Chen

Let's say that we did want to support Move in our drag/drop program, for whatever reason. Let's do it with some scratch file instead of clock.avi, though. Create a file somewhere that you don't mind losing; let's say it's C:\throwaway.txt. Change the function OnLButtonDown as follows: void OnLButtonDown(HWND hwnd, BOOL fDoubleClick...

Dragging a shell object, part 1: Getting the IDataObject

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

Raymond Chen

The shell gives you the IDataObject; all you have to do is drag it around.

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

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

Raymond Chen

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?

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

Raymond Chen

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?

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

Raymond Chen

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

What’s the difference between GetKeyState and GetAsyncKeyState?

November 30, 2004 Nov 30, 2004 11/30/04

Raymond Chen

I've seen some confusion over the difference between the function and the function. returns the virtual key state. In other words, reports the state of the keyboard based on the messages you have retrieved from your input queue. This is not the same as the physical keyboard state: When should you use and when should you use...