backdropper: fixed type error

[thomjiji]

Set NUKE_PATH evironment variable to point to nuke-config directory (set -x NUKE_PATH nuke-config $NUKE_PATH — in fish shell), then start Nuke from Terminal, press shift+b to try to open up backdropper, it will report error:

Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/Users/thom/repos/nuke-config/scripts/nuketools/backdropper.py", line 482, in invoke
    panel = BackdropPanel(QtWidgets.QApplication.activeWindow())
  File "/Users/thom/repos/nuke-config/scripts/nuketools/backdropper.py", line 104, in __init__
    self.setup_nodes()
  File "/Users/thom/repos/nuke-config/scripts/nuketools/backdropper.py", line 270, in setup_nodes
    self.set_sliders()
  File "/Users/thom/repos/nuke-config/scripts/nuketools/backdropper.py", line 330, in set_sliders
    self.appearance_checkbox.setChecked(self.bd['appearance'].getValue())
TypeError: 'float' object cannot be interpreted as an integer

The backdropper GUI didn't open up.

It seems like a type error. Fixing it with the commit works on my machine (MBP M1).