Saving onscreen graphics fails

[drogenlied]

What is affected by this bug?

Windows8, Linux on master in default Conda environment. Multiple modules that save data.

When does this occur?

Example: wavemeterlogger module. In the menu, choose Laserscan > Save. It is also possible to trigger this from the Export option of the right click menu on any pyqtgraph plot.

Where on the platform does it happen?

How do we replicate the issue?

Traceback (most recent call last):
  File "/home/jan/qo/qudi/gui/wavemeterlogger/wavemeterloggui.py", line 306, in save_clicked
    exporter.export(filename+'.png')
  File "/usr/lib/python3/dist-packages/pyqtgraph/exporters/ImageExporter.py", line 70, in export
    bg = np.empty((self.params['width'], self.params['height'], 4), dtype=np.ubyte)
TypeError: 'float' object cannot be interpreted as an integer

This is a pyqtgraph bug. See https://github.com/pyqtgraph/pyqtgraph/issues/454.

Expected behavior (i.e. solution)

No exception.

##Other Comments A newer version of pyqtgraph fixes this, but introduces other issues.