No New Timer Events During Visual Basic Timer Event Processing

ID Number: Q78599

1.00

WINDOWS

Summary:

Timer controls can be used to automatically generate an event at

predefined intervals. This interval is specified in milliseconds, and

can range from 0 to 64767 inclusive.

Timer event processing will not be interrupted by new timer events.

This is because of the way that Windows notifies an application that a

timer event has occurred. Instead of interrupting the application,

Windows places a WM_TIMER message in it's message queue. If there is

already WM_TIMER message in the queue from the same timer, the new

message will be consolidated with the old one.

After the application has completed processing the current timer

event, it checks it's message queue for any new messages. This queue

may have new WM_TIMER messages to process. There is no way to tell if

any WM_TIMER messages have been consolidated.

This information applies to Microsoft Visual Basic programming system

version 1.0 for Windows.

Reference(s):

"Programming Windows: The Microsoft Guide to writing applications for

Windows 3.0," Charles Petzold, Microsoft Press, 1990

Additional reference words: 1.00