Switching to Double Hi-Res (DHGR) within a program

[vectorthom <greg.rossiter@gmail.com>]

Hello all,

I'm trying to learn how to use Double Hi-Res graphics on the Apple
II.  I've recently acquired an Apple IIe to replace one my family sold
years ago and am reliving my '80s childhood through old floppy disks
that I still have on-hand.  I don't remember even knowing about double
hi-res graphics back then, but I'd like to start experimenting with it
now.  I have Broderbund's Dazzledraw (a DHGR program) and a bunch of
homemade drawings saved to disk.  I have a Rev. B Apple IIe and an 80
col/64k expansion card, so I believe I have the machine capability to
display DHGR.  At the prompt, I know that entering "PR#3" will switch
me to 80 column mode, where all the text gets visibly thinner.  Is
this essentially DHGR mode or is there more to it than that?

My main question however is this:  how do I switch to DHGR mode once
I'm within a program?  As said, I can switch to 80 column mode when
I'm at the prompt, but when I reboot to start loading Dazzledraw for
example, it hops back to 40 column mode.  I don't see a way to switch
back from within the program.  I'm curious to know if I'm viewing my
created images at their best or if they would look better in 80 column
mode. Is there a relatively easy way to toggle back and forth between
video modes?

Thanks,
Greg R