After saving a file, next time it is reloaded I keep having trouble that display of transparency frequently is lost on more complicated objects but not the transparency parameter. Initially I thought this had to do with objects originally imported from STEP files (where after transparency was set), however I have now been able to isolate a the simple case of an extruded object with multicolored faces where transparency display is lost on file load.
To reproduce (tested with latest development version on Win7, but I have experienced these problems for a long time, also in stable ver. 0.18):
1. Create a simple shape, for instance a rectangle and extrude it. Mark it and apply transparency under the view tab, for instance set it to 80% and observe correct display. Save and close file. Reload it and observe correct display of transparency.
2a. Mark object, right click, Set Colors, mark one of the faces and change color. Keep transparency. Transparency is still corretly displayed. Save file and close it. Reload file. Observe transparency display gone but color is correct, and on inspection the transparency parameter under the view tab is still at 80%.
2b. Close file without saving and reload again (transparency gone). Mark object and change color so that it gets a single color. Transparency is back again. Save file, close and reload. Transparency is now correct.
2c. Close file without saving and reload again (transparency gone). Change transparency (for instance to 81%). Observe correct transparency being displayed again. Save, close and reload. Transparency display is gone again.
Is this a bug, or an inherent "feature"? It would seem that because a simple thing as making a change to the transparency parameter can make it appear again, a routine that would bring back transparency display could be performed on file load?
Could the problems be related to this fairly recent change that can allow per face transparency to be set?
The attached files show the results of the different tests above.
OS: Windows 7 SP 1 (6.1)
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.19.18760 (Git)
Build type: Release
Python version: 3.6.7
Qt version: 5.12.1
Coin version: 4.0.0a
OCC version: 7.3.0
Locale: English/United States (en_US)
(For the record I am using a Nivida graphics card)