Comment 6 for bug 1516428

1. the same goes for Synaptics Touchpad (with libinput), which cannot be enabled. So it's not possible to click with the touchpad at all if there is a wacom tablet/pen being used. This means you can either have a pen or the mouse but not both. The mouse can however click in the menus.

2. the workaround for the problem mentioned before by others is to set all those things manually in ~/.config/inkscape/preferences.xms to mode="screen". It then looks like this:
  <group
     id="devices">
    <group
       id="P:Wacom Co.,Ltd. Pen and multitouch sensor Pen stylus"
       mode="screen"
       axes="x;y;pressure;xtilt;ytilt;wheel"
       keys="" />
    <group
       id="E:Wacom Co.,Ltd. Pen and multitouch sensor Pen eraser"
       mode="screen"
       axes="x;y;pressure;xtilt;ytilt;wheel"
       keys="" />
    <group
       id="P:Wacom Co.,Ltd. Pen and multitouch sensor Finger"
       mode="screen"
       axes="x;y;pressure;xtilt"
       keys="" />
  </group>