A common feature for many applications is to record their screen location when they shut down and reopen at that location when relaunched. If implemented naively, a program merely restores from its previous position unconditionally. You run into usability problems with this naive implementation. If a user runs two copies of your program, the two w...
The weekend of March 12th and 13th, Vegetarians of Washington is hosting VegFest 2005, a festival of vegetarian food. This reminds me of a Time Magazine cover story from July 2002, wherein it was revealed that... In a survey of 11,000 individuals, 37% of those who responded "Yes, I am a vegetarian" also reported that in the previous 24 hours t...
In the operating systems group, we have to take a holistic view of performance. The goal is to get the entire system running faster, balancing applications against each other for the greater good. Applications, on the other hand, tend to have a selfish view of performance: "I will do everything possible to make myself run faster. The impact on th...
If you pass the flag to the function, it will broadcast the message with the wParam equal to the system parameter code you passed. For example, if you call then the system will broadcast the message If there is a window that isn't responding to messages, then this broadcast will hang until that unresponsive window finally resumes respon...
The function gives you access to a whole slew of user interface settings, and it is the only supported method for changing those settings. I'm not going to list every single setting; go read the list yourself. Here are some highlights: Here are some control panel settings. Notice that when using the SPI_SET* commands, you also have to choo...
Remember that there are typically two 8-bit code pages active, the so-called "ANSI" code page and the so-called "OEM" code page. GUI programs usually use the ANSI code page for 8-bit files (though utf-8 is becoming more popular lately), whereas console programs usually use the OEM code page. This means, for example, when you open an 8-bit text fil...
This is sort of in the same spirit as our previous exercise in writing a timed message box, but this is much easier. Here, we use the handy-dandy message to get us out of menu mode. Before displaying the menu, we set a timer. (And we use a thread timer because we don't own the window and therefore don't know what timer IDs are safe to use.)...
A few days ago, we saw a simple version of a timed message box which had a limitation that it could be used from only one thread at a time. Today we'll work to remove that limitation. As you may recall, the reason why it could be used from only one thread at a time was that we kept the "Did the message box time out?" flag in a global. To fix i...
My random walk began at Svenska Dagbladet and the article Svensk designer upprör skottar, about Swedish designer Johanna Larson whose T-shirt depicting the traffic-cone-wearing Duke of Wellington has sparked a debate in the city. The article mentions that the tradition of placing a traffic cone on the head of the Duke is twenty years old, an...
The window manager provides a pointer-sized chunk of storage you can access via the constant. You pass it to the function and the function to read and write that value. Most of the time, all you need to attach to a window is a single pointer value anyway, so the free memory in is all you need. Note that this value, like the other window ext...
