Issue with lyx and recent dll

[Ken Brown]

On 6/3/2020 4:34 PM, Enrico Forestieri wrote:
> On Mon, Jun 01, 2020 at 10:26:05PM +0200, Marco Atzeri wrote:
>> On 29.05.2020 17:29, Enrico Forestieri wrote:
>>> On Thu, May 28, 2020 at 10:01:15PM +0200, Marco Atzeri via Cygwin wrote:
>>>> On 28.05.2020 20:25, Enrico Forestieri wrote:
>>>>> On Thu, May 28, 2020 at 08:09:49PM +0200, Marco Atzeri via Cygwin wrote:
>>>>>>
>>>>>> after installing also another package
>>>>>> texlive-collection-pstricks
>>>>>>
>>>>>> I was able to have an instant preview
>>>>>>
>>>>>> can you check if the test 2.3.4.2-2
>>>>>> solve the issue also for you ?
>>>>>> Than I can promote it to stable
>>>>>
>>>>> Yes, that did it! I am curious to know how you compiled it, because I see
>>>>> the same strange behavior when compiling lyx from source.
>>>>>
>>>>
>>>>
>>>> --enable-qt5 PYTHON="python3"
>>>
>>> Doh!
>>
>> I also patched the source to replace python with python3 in all
>> the scripts.
>>
>>>
>>> Nevertheless, it remains a mystery why I had to revert to cygwin 3.0.7
>>> for having instant preview working with the Qt4 version.
>>
>> No idea on this.
> 
> I found that this is due to having defined "LyXServer pipe" in
> Tools>Preferences>Paths. Specifying there the path for the fifo results
> in instant preview not working. Removing it, instant preview works
> again. The puzzling part is that it seems to always work on a computer
> regardless of "LyXServer pipe", while it works on another one only if
> the "LyXServer pipe" field is left empty.
> 
> Instead, with cygwin 3.0.7 it seems to always work.

There were some major changes in Cygwin's fifo implementation in cygwin 3.1.0. 
It doesn't seem to have gotten a lot of testing until fairly recently, when some 
bugs were discovered and fixed in cygwin 3.1.5.  Have you tried the latter? 
(There's also some new functionality for fifos in cygwin 3.1.5, but I doubt if 
that's relevant to your issue.)

Ken