On one of our internal discussion mailing lists, someone posted the following question: We have some code that was using DragQueryFile to extract file paths. The prototype for DragQueryFile appears as follows: UINT DragQueryFile( HDROP hDrop, UINT iFile, LPTSTR lpszFile, UINT cch ); In the code we have, instead of passing an ...

Now that you know how the 16-bit memory manager handled the global heap, it's time to see how this got transitioned to the new 32-bit world. The function continued to emulate all its previous moveability rules, but the return value of was no longer a selector since Win32 used the processor in "flat mode". This means that the old trick of ca...

I think it is a trait common to many people that they are fascinated by how their country is viewed by others. The leftist Die Tageszeitung from Germany reacted to the result of the most recent U.S. presidential election with their list of one hundred things that are still better in the United States. Those who cannot read German can use a tra...

With the advent of the 80286, Windows could take advantage of that processor's "protected mode". processor. There was still no virtual memory, but you did have memory protection. Global handles turned into "descriptors", more commonly known as "selectors". Architectural note: The 80286 did have support for both a "local descriptor table" and a ...

Once upon a time, there was Windows 1.0. This was truly The Before Time. 640K. Segments. Near and far pointers. No virtual memory. Co-operative multitasking. Since there was no virtual memory, swapping had to be done with the co-operation of the application. When there was an attempt to allocate memory (either for code or data) and insuffici...

If you read through old code, you will often find casts that seem redundant. SendMessage(hwndListBox, LB_ADDSTRING, 0, (LPARAM)(LPSTR)"string"); Why was "string" cast to LPSTR? It's already an LPSTR! These are leftovers from 16-bit Windows. Recall that in 16-bit Windows, pointers were near by default. Consequently, "string" was a near pointe...

The GlobalAlloc function has a GMEM_SHARE flag. What was it for? In 16-bit Windows, the GMEM_SHARE flag controlled whether the memory should outlive the process that allocated it. By default, all memory allocated by a process was automatically freed when that process exited. Passing the GMEM_SHARE flag suppressed this automatic cleanup. That's...

According to the Constitution of the State of New Jersey, Article II, paragraph 6: No idiot or insane person shall enjoy the right of suffrage. Why are constitutional articles labelled with Roman numerals? Makes it sound like the Super Bowl or something. The state appellate court did rule a few years ago that being hospitalized...

Back in the days of 16-bit Windows, the difference was significant. In 16-bit Windows, memory was accessed through values called "selectors", each of which could address up to 64K. There was a default selector called the "data selector"; operations on so-called "near pointers" were performed relative to the data selector. For example, if you had ...

The taskbar created all sorts of interesting problems, since the work area was not equal to the entire screen dimensions. (Multiple monitors created similar problems.) "Why didn't the gui return the usable workspace as the root window (excluding the taskbar)?" That would have made things even worse. Lots of programs want to cover the entire sc...