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Computing the interval between two moments in time is easy: It's just subtraction, but subtraction may not be what you want. If you are displaying time units on the order of months and years, then you run into the problem that a month is of variable length. some people just take the value relative to a base date of January 1 and extract the yea...

What a boring title. Often you'll find yourself needing to perform a multi-level comparison. The most common example of this is performing a version check when there are major and minor version numbers involved. Bad version number checks are one of the most common sources of errors. If you're comparing version numbers, you can use the funct...

Injecting accelerator keys into the dialog modal loop.

Some dialog boxes contain custom navigation that goes beyond what the function provides. For example, property sheets use Ctrl+Tab and Ctrl+Shift+Tab to change pages within the property sheet. Remember the core of the dialog loop: (Or the modified version we created in part 7.) To add custom navigation, just stick it in before callin...

Last time, we solved the problem with the function by posting a harmless message. Today, we're going to solve the problem in an entirely different way. The idea here is to make sure the modal message loop regains control, even if all that happened were incoming sent messages, so that it can detect that the flag is set and break out of the mod...

Last time, I left you with a homework exercise: Find the subtle bug in the interaction between and the modal message loop. The subtlety is that sets some flags but does nothing to force the message loop to notice that the flag was actually set. Recall that the function does not return until a posted message arrives in the queue. If incomin...

Let's apply what we learned from last time and convert a modeless dialog box into a modal one. As always, start with the scratch program and make the following additions: Not a very exciting program, I grant you that. It just displays a dialog box and returns a value that depends on which button you pressed. The function uses the function t...

The dialog loop is actually quite simple. At its core, it's just If you want something fancier in your dialog loop, you can take the loop above and tinker with it. But let's start from the beginning. The work happens in DialogBoxIndirectParam. (You should already know by now how to convert all the other DialogBoxXxx functions into DialogBoxInd...

This is actually a lot less work than creating the frame, believe it or not. For each control in the template, the corresponding child window is created. The control's sizes and position is specified in the template in DLUs, so of course they need to be converted to pixels. The class name and caption also come from the template. There are al...

The dialog template describes what the dialog box should look like, so the dialog manager walks the template and follows the instructions therein. It's pretty straightforward; there isn't much room for decision-making. You just do what the template says. For simplicity, I'm going to assume that the dialog template is an extended dialog template....