Workaround: Don't use Mma 11.2.0 w/ Xtightvnc; use it native, or via ssh -X or xrdp using Xorg on up-to-date (stretch) Raspbian installations.
I recently upgraded a Raspberry Pi 2 and Raspberry Pi 3 (both kept up-to-date, and running stretch), and the new wolfram-engine got updated to 11.2.0+2018011502 armhf.
Mma 11.2.0 does work (only checked on the RPi 3) on the native display, and via ssh -X from a (up to date) CentOS 7, and via xrdp using Xorg as the server on RPi 2 -- it's just the Xtightvnc version on the RPi that fails. That's xtightvncviewer 1:1.3.9-9 armhf.
The problem manifests as a silent windows-go-away after startup, triggered by mouse-overs on the small window with the icons (or attempted data entry in the notebook).
By attaching gdb to the front end right after startup but before mouse overs, I discovered the following failure on subsequent mouse overs; note that where it died is a bit of a red herring, since the memory state has already been damaged -- the stack is reported as corrupt.
(gdb) catch signal
Catchpoint 1 (standard signals)
[Thread 0x6e1762e0 (LWP 18285) exited]
[Thread 0x6f48a2e0 (LWP 18281) exited]
[Switching to Thread 0x6ffff2e0 (LWP 18280)]
Thread 7 "Qt bearer threa" hit Catchpoint 1 (signal SIGSEGV), 0x75853c68
in QNetworkConfigurationManagerPrivate::pollEngines() ()
#0 0x75853c68 in QNetworkConfigurationManagerPrivate::pollEngines() ()
#1 0x758e9194 in ?? () from /opt/Wolfram/WolframEngine/11.2/SystemFiles/Libraries/Linux-ARM/libQt5NetworkWRI.so.5
Backtrace stopped: previous frame identical to this frame (corrupt stack?)
I'm pretty sure Mathematica provided with wolfram-engine 11.0.1+2017071100 used to work over vnc using Xtightvnc -- it no longer does, on either the RPi 2 or RPi 3. Non-GUI "wolfram" is fine.
So it very much looks like the new version of wolfram-engine, 11.2.0, released for Raspberry Pi's has a problem with certain (less capable) X servers, specifically Xtightvnc.
FYI, the Xtightvnc server has limited extensions, and lacks GLX etc. Here's some xdpyinfo from Xtightnvc.
name of display: :3.0
version number: 11.0
vendor string: AT&T Laboratories Cambridge
vendor release number: 3332
maximum request size: 4194300 bytes
motion buffer size: 256
bitmap unit, bit order, padding: 32, LSBFirst, 32
image byte order: LSBFirst
number of supported pixmap formats: 2
supported pixmap formats:
depth 1, bits_per_pixel 1, scanline_pad 32
depth 24, bits_per_pixel 32, scanline_pad 32
keycode range: minimum 8, maximum 255
focus: window 0x4000030, revert to Parent
number of extensions: 7
default screen number: 0
number of screens: 1
I hope you find this useful.
Thanks for the useful and detailed report, it's been passed to the developers/QA team.