Ok, this might be a bit of a weird one, but I just managed to produce a problem that I've been meaning to reproduce for a while now:

Sometimes, when I and rendering something to disk while the preview is still also rendering, all UF windows start flickering erratically and the program becomes all but uncontrollable. In most cases I can somehow hunt down the window in question and close it or pause the rendering to disk, but in some rare cases it just crashes instead.

How to produce the bug:

- open a few windows with different fractals, I had 6 fractals open in this case
- I opened a 7th fractal (parameters below)
- I started rendering the 7th fractal to disk in 16k resolution and hilarity ensued

The only way to stop the flickering and jumping between UF windows was to either close fractal 7 or let it finish rendering the preview. The window swapping also continues in the background while other programs are usable normally.

Here's the fractal in question:

```
27 {
::CXMCuin2tLVsOuNMM09Ak/BBvnERJLZrWoheLd5GuhuXozW2W4klMkVav83XalcBXLK6UXKQ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}
Gnarls.ufm:gnarltest9b {
; Original formula otto magus
; modified Evan Bayliss May 2021, April 2022
; Three chosen gnarlic formulae are calculated
; One result iterates into the next
; Three chosen post function formulae are concurrently calculated -
; one after each gnarlic formula
; The final post function values are combined using Statistics derived from
; jlb.ucl and the Physicist 12 August 2021 Forum Post
; simplified to play around with by Phillip S.
::TgUwegn2NCVXrRMIQw3F8/wSKFyHHhkDuHuSFC9fiNxcsgRFjHkEuf8dN2c0Xap+i7Oz4MrL
nhGM8GntBC4FHuo0cGnADAhr8EaDnptWHpZxqHIAvSqz3K4s1UPOJvt37tBqt3On3RlFQFk3
cCaLgSYGNJQy7xk1veGE7uDwC9sdzrgOX73yjuXEZXJ21fyGTY5gNO4LPjqEWPA3i6tjjzqQ
Lnp0zqfNq26LU1fHYSz/J2Sg+oUimBckzOWjp7KgmlPlo2ePu1fs949uYLnNoGl31RwAG0KR
2MO50K4mR61B1cAumxZTyloPiL0erXZil5N1ngm6iI5Nj4Mn5Ue0Og9YYVQ6cSvcCSp0LdB0
aEZfkmhsnBLabSn6m9Zf/Vc2X8e6VKG=
}
phs.ucl:GnarlAlgo {
::LnRrHin2tW1yutNMQw7Gw/DLsvY5g4mmjBxAxJooXyhgmcsAFbkokJAFpg06WH/1X+SPMjoS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}
```