Invoking PieMenu in a certain condition displays 2 PieMenus glitch

[luzpaz]

Reproduce:

1. Click tab to invoke PieMenu
2. move mouse over
3. press esc
4. press tab
   Result: screen flickers with 2 PieMenus until the previous one disappears

Running PieMenu b04d6bc
OS: "Manjaro Linux"
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.18.14959 (Git) AppImage
Build type: Release
Branch: master
Hash: ff05101b68dc9a7d1e70dd69544f14ac8598a433
Python version: 2.7.6
Qt version: 4.8.6
Coin version: 4.0.0a
OCC version: 7.3.0
Locale: English/UnitedStates (en_US)