I am reporting this bug here as required under the devs bug report rules.
Please comment !
I have a clean version of FreeCAD 0.18, installed yesterday (17 July 2019) and has not been used for anything yet as I am a comletely new user.
I have followed and studied YouTube tutorials e.g. https://www.youtube.com/watch?v=mavbz1Zpkws
But to simplify :
Event sequence :
1. Open FreeCAD
2. Create "New"
3. Set "Navigation Style" to "Gesture"
4. Set Workbench to "Part"
5. Create primitive shape (Box)
6. Left-Click on the box (& drag a little to show 3D (but this is not necessary to generate the bug !))
7. At this point I have included a screen snapshot (see attached file)
8. Select tab "View" and attempt to change transparency parameter by entering "70" in the "Value" column.
9. as soon as I type the first digit "7", the navigation widget dissappears and the transparency is not correctly set. This state is unrecoverable in the current view. See screenshots shown in attached file. and after dragging the box around . .
Note that the displayed box appears exactly the same whatever transparency value I set, from 1 to 100.
The program appears to run much slower from this point on and dragging the box takes seconds to refresh rather than being instantaneous..
10. This may be unrelated, but subsequently, I re-sized the WINDOWS app window by dragging the top left-hand side box on the Windows 10 app window. An error message appeared in RED in the FreeCAD notification bar and I have also attached this message in a jpg file.
Note : This error does not happen in normal operation of FreeCAD, only after the transparency error has occured.
System capture :
OS: Windows 10
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.18.16117 (Git)
Build type: Release
Python version: 3.6.6
Qt version: 5.6.2
Coin version: 4.0.0a
OCC version: 7.3.0
Locale: English/UnitedKingdom (en_GB)