Hello,
I use default themes and have no issues with a two monitor setup.
~$ inxi -xGc0
Graphics: Card: NVIDIA GF108 [GeForce GT 530] bus-ID: 01:00.0
Display Server: X.Org 1.18.4 drivers: nvidia,fbdev,vesa,nouveau
Resolution: 1920x1080@60.00hz, 1920x1080@60.00hz
GLX Renderer: GeForce GT 530/PCIe/SSE2 GLX Version: 4.5.0 NVIDIA 361.45.18 Direct Rendering: Yes
greetings
musca