Clock change notification at DST change

Simple really, does Windows send a WM_TIMECHANGE message to all programs when
the daylight saving time shift occurs? I suspect not, but what if I want my
application to "know" that DST has become/stopped being operative?

Some applications rely on the local computer clock some do not. You would
have to research each application to find out how they get their time.

"TechoMad" wrote:

> Simple really, does Windows send a WM_TIMECHANGE message to all programs when
> the daylight saving time shift occurs? I suspect not, but what if I want my
> application to "know" that DST has become/stopped being operative?

The application does use the clock, that is why I asked - if it didn't, it
wouldn't matter. The question still stands, when a daylight saving point is
reached, does the Windows OS inform the applications through a WM_TIMECHANGE
message, so they are aware of the event?

"MPaquette" wrote:

> Some applications rely on the local computer clock some do not. You would
> have to research each application to find out how they get their time.
>
> "TechoMad" wrote:
>
> > Simple really, does Windows send a WM_TIMECHANGE message to all programs when
> > the daylight saving time shift occurs? I suspect not, but what if I want my
> > application to "know" that DST has become/stopped being operative?

No.

TechoMad wrote:
> The application does use the clock, that is why I asked - if it didn't, it
> wouldn't matter. The question still stands, when a daylight saving point
> is
> reached, does the Windows OS inform the applications through a
> WM_TIMECHANGE
> message, so they are aware of the event?
>
> "MPaquette" wrote:
>
>> Some applications rely on the local computer clock some do not. You
>> would
>> have to research each application to find out how they get their time.
>>
>> "TechoMad" wrote:
>>
>>> Simple really, does Windows send a WM_TIMECHANGE message to all programs
>>> when the daylight saving time shift occurs? I suspect not, but what if I
>>> want my application to "know" that DST has become/stopped being
>>> operative?

Disappointing if confirmed; I've now run a test and it looks like it does on
SP3, I need to repeat the run on SP2.

"PA Bear [MS MVP]" wrote:

> No.
>
> TechoMad wrote:
> > The application does use the clock, that is why I asked - if it didn't, it
> > wouldn't matter. The question still stands, when a daylight saving point
> > is
> > reached, does the Windows OS inform the applications through a
> > WM_TIMECHANGE
> > message, so they are aware of the event?
> >
> > "MPaquette" wrote:
> >
> >> Some applications rely on the local computer clock some do not. You
> >> would
> >> have to research each application to find out how they get their time.
> >>
> >> "TechoMad" wrote:
> >>
> >>> Simple really, does Windows send a WM_TIMECHANGE message to all programs
> >>> when the daylight saving time shift occurs? I suspect not, but what if I
> >>> want my application to "know" that DST has become/stopped being
> >>> operative?
>
>

Tests on SP2 and SP3 show that a WM_TIMECHANGE event does arrive when the
daylight saving change events occur, so that's all right then - I can make my
program do what I need.

"PA Bear [MS MVP]" wrote:

> No.
>
> TechoMad wrote:
> > The application does use the clock, that is why I asked - if it didn't, it
> > wouldn't matter. The question still stands, when a daylight saving point
> > is
> > reached, does the Windows OS inform the applications through a
> > WM_TIMECHANGE
> > message, so they are aware of the event?
> >
> > "MPaquette" wrote:
> >
> >> Some applications rely on the local computer clock some do not. You
> >> would
> >> have to research each application to find out how they get their time.
> >>
> >> "TechoMad" wrote:
> >>
> >>> Simple really, does Windows send a WM_TIMECHANGE message to all programs
> >>> when the daylight saving time shift occurs? I suspect not, but what if I
> >>> want my application to "know" that DST has become/stopped being
> >>> operative?
>
>

I'm glad I forced you to do your own research.

TechoMad wrote:
> Tests on SP2 and SP3 show that a WM_TIMECHANGE event does arrive when the
> daylight saving change events occur, so that's all right then - I can make
> my program do what I need.
>
> "PA Bear [MS MVP]" wrote:
>
>> No.
>>
>> TechoMad wrote:
>>> The application does use the clock, that is why I asked - if it didn't,
>>> it
>>> wouldn't matter. The question still stands, when a daylight saving point
>>> is
>>> reached, does the Windows OS inform the applications through a
>>> WM_TIMECHANGE
>>> message, so they are aware of the event?
>>>
>>> "MPaquette" wrote:
>>>
>>>> Some applications rely on the local computer clock some do not. You
>>>> would
>>>> have to research each application to find out how they get their time.
>>>>
>>>> "TechoMad" wrote:
>>>>
>>>>> Simple really, does Windows send a WM_TIMECHANGE message to all
>>>>> programs
>>>>> when the daylight saving time shift occurs? I suspect not, but what if
>>>>> I
>>>>> want my application to "know" that DST has become/stopped being
>>>>> operative?