Building a dialog template at run-time

Raymond ChenApril 29, 2005Apr 29, 200504/29/05

We've spent quite a bit of time over the past year learning about dialog templates and the dialog manager. Now we're going to put the pieces together to do something interesting: Building a dialog template on the fly. What we're going to write is an extremely lame version of the MessageBox function. Why bother writing a bad version of ...

Rescuing thread messages from modal loops via message filters

Raymond ChenApril 28, 2005Apr 28, 200504/28/05

As we have seen recently, thread messages are eaten by modal loops because they have nowhere to go when dispatched. However, there is a way to see them before they vanish, provided the modal loop is cooperative. The WH_MSGFILTER message hook allows you to receive messages passed to the CallMsgFilter function. Fortunately, all the modal ...

Watching thread messages disappear

Raymond ChenApril 27, 2005Apr 27, 200504/27/05

We saw last time that thread messages are eaten by modal loops. Today we'll illustrate, and then we'll try to fix it next time. Start with our scratch program and make the following changes: Run this program and notice that it beeps every two seconds, or at least it does most of the time. If you right-click on the caption bar or grab ...

Thread messages are eaten by modal loops

Raymond ChenApril 26, 2005Apr 26, 200504/26/05

Thread messages (as generated by the PostThreadMessage function) do not go anywhere when passed to the DispatchMessage function. This is obvious if you think about it, because there is no window handle associated with a thread message. DispatchMessage has no idea what to do with a message with no associated window. It has no choice but to ...

What is the HINSTANCE passed to SetWindowsHookEx used for?

Raymond ChenApril 25, 2005Apr 25, 200504/25/05

The SetWindowsHookEx function accepts a HINSTANCE parameter. The documentation explains that it is a handle to the DLL containing the hook procedure. Why does the window manager need to have this handle? It needs the handle so it knows which DLL to load into each process when the hook fires. It injects the DLL you pass, then calls the ...

The new scratch program

Raymond ChenApril 22, 2005Apr 22, 200504/22/05

I think it's time to update the scratch program we've been using for the past year. I hear there's this new language called C++ that's going to become really popular any day now, so let's hop on the bandwagon! The basic idea of this program is the same as our old scratch program, but now it has that fresh lemony C++ scent. Instead of ...

The Itanium’s so-called stack

Raymond ChenApril 21, 2005Apr 21, 200504/21/05

Last year I alluded to the fact that the Itanium processor has two stacks. The one that is traditionally thought of as "the stack" (and the one that the sp register refers to) is a manually managed block of memory from which a function can carve out space to use during its execution. For example, if you declare a local variable like then ...