Hello!
Finally I've solved it! 
First I had no idea because the internet wasn't that helpful. Than I remembered this here:
"On 12 February 2013, Opera announced it would drop its own Presto engine in favour of WebKit as implemented by Google's Chrome browser, using code from the Chromium project."
So I've copied the lines for the Chrome Broswer and replaced "chrome.exe" with "opera.exe". It works!
<ap name="opera.exe" class_name="Chrome_WidgetWin_0" target_name="Chrome_RenderWidgetHostHWND" title_name="" target_type="0" support="33413" pan_filter_x="5" pan_filter_y="5" zoom_filter="1" pan_type="15" es_filter="5" es_type="15" zoom_type="0" rotate_type="0" swipe_type="3"/>
<ap name="opera.exe" class_name="Chrome_WidgetWin_1" target_name="Chrome_WidgetWin_1" title_name="" target_type="0" support="33413" pan_filter_x="5" pan_filter_y="5" zoom_filter="1" pan_type="15" es_filter="5" es_type="15" zoom_type="0" rotate_type="0" swipe_type="3"/>
<ap name="opera.exe" class_name="Chrome_WidgetWin_1" target_name="Chrome_RenderWidgetHostHWND" title_name="" target_type="0" support="33413" pan_filter_x="5" pan_filter_y="5" zoom_filter="1" pan_type="15" es_filter="5" es_type="15" zoom_type="0" rotate_type="0" swipe_type="3"/>
Save the modified file (open file as admin, e.g. with Notepad++), reboot your system, be happy!
Greetings
Ann