Ah I had an extra underscore in the environment variable. Thank you! I ran it again (calibre-debug.exe --viewer) and the ebook window shows up now, but the contents of the window are all blank / not visible.
Here is the debug output:
Code:
QPA platform: windows
devicePixelRatio: 1.0
logicalDpi: 96.0 x 96.0
physicalDpi: 81.55183946488295 x 81.64285714285714
ApplicationPaletteChange event ignored
Using calibre Qt style: True
ApplicationPaletteChange event received
QWindowsGLContext::makeCurrent: wglMakeCurrent() failed (The operation completed successfully.)
QRhiGles2: Failed to make context current. Expect bad things to happen.
Failed to create QRhi for QBackingStoreRhiSupport
[0.000] Load of book started
[0.015] prepared emitted
[0.078] webview loading requested
[0.281] bridge ready
[0.390] iframe ready
[0.453] loading finished
If I mouse over the window I can see the cursor change as it goes over text, and can copy/paste text from the ebook, however it's all just not visible. It's the same when opening ebooks directly from Calibre as well.