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Font problem

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Hi

I'm struggling with a mysterious problem.

I have a BASIC program which can be launched three ways - run directly, or 
run via Wimp_StartTask from one of two different programs. When it is 
launched via one of those programs it changes the desktop font to the 
System font. This occurs if the launching program starts up using "run at 
startup" but not if it is run manually.

(This is a bit over-simplified - I can reproduce the problem using the 
above, but I have seem intermittent effects affecting the font on other 
occasions.)

It uses a pane window which contains a varying number of icons. This 
problem occurs just after the number of icons is increased from 1 to 3 by 
copying the first one downwards.

Within the code, the change of font occurs at the first Wimp_Poll, which 
is after the windows are manipulated and opened.

If Organiser is running at that point it crashes with "invalid font 
handle".

When the launched program puts text into some of its icons, no text is 
displayed.

This program is the only one of my set to use a specified font in its 
icons, so this could be related. The Wimp_LoadTemplate does contain a 
pointer to a 256 byte font handle block, which has been initialised with 
0's first. I have tried DIMming unused blocks before and after this, with 
no effect on the results. I've tried increasing the Wimp slot, and 
increasing the size of all the buffers used in manipulating the windows.

My suspicion, as always in such cases, is to suspect that something I am 
doing is overwriting memory somewhere. Can anyone come up with a reason 
for the desktop font change to be the result?

-- 
Alan Adams, from Northamptonshire
alan@adamshome.org.uk
http://www.nckc.org.uk/

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Font problem Alan Adams <alan@adamshome.org.uk> - 2019-05-10 19:25 +0100
  Re: Font problem Alan Adams <alan@adamshome.org.uk> - 2019-05-10 19:35 +0100
    Re: Font problem Alan Adams <alan@adamshome.org.uk> - 2019-05-10 20:19 +0100
  Re: Font problem Matthew Phillips <spam2011m@yahoo.co.uk> - 2019-05-10 21:21 +0100
  Re: Font problem Harriet Bazley <harriet@bazleyfamily.co.uk> - 2019-05-11 01:20 +0100
  Re: Font problem Paul Sprangers <Paul@sprie.nl> - 2019-05-11 14:28 +0200
    Re: Font problem Alan Adams <alan@adamshome.org.uk> - 2019-05-12 20:44 +0100
      Re: Font problem Martin Wuerthner <spamtrap@mw-software.com> - 2019-05-13 19:43 +0200
        Re: Font problem Alan Adams <alan@adamshome.org.uk> - 2019-05-13 21:54 +0100
        Re: Font problem Alan Adams <alan@adamshome.org.uk> - 2019-05-14 11:57 +0100
      Re: Font problem jgh@mdfs.net - 2019-05-14 21:10 -0700
        Re: Font problem Alan Adams <alan@adamshome.org.uk> - 2019-05-15 10:11 +0100

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