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Maniphest T83035

Nodes or node connections can't be dragged with mouse
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Description

System Information
Operating system: Linux Mint 20 - XFCE
Graphics card: Nvidia RTX 2070
Graphics card driver: Nvidia 455.38
Window manager: XFWM4
Display manager: X11

system-info.txt21 KBDownload

Blender Version
Broken: All versions tested (2.78, 2.8, 2.9, 2.91)

Short description of error
I can't drag nodes or node connections using the mouse.
A GIF to demonstrate (with screen-cast keys enabled)


Exact steps for others to reproduce the error

  1. Run any version of Blender with the above display manager, GPU and driver.
  2. Open any blend file and try to move a node by dragging the mouse over it.

Additional Information
The console seems to have the same message spammed a lot of times:

Bad keycode lookup. Keysym 0x0 Status: XLookupNone
'' 0x7f7108318b80 0x7f712f57fb40

Event Timeline

Denver P. (Obsyden) created this task.Nov 26 2020, 8:06 AM
Robert Guetzkow (rjg) added a subscriber: Robert Guetzkow (rjg).Nov 26 2020, 11:09 AM

This seems like Blender is getting bad key-stroke events, but it is strange that screen-cast keys reports the correct buttons. This still looks more like an issue with X11 / your window manager. It might intermittently send wrong key codes while dragging?

Robert Guetzkow (rjg) added a project: User Interface.Nov 26 2020, 11:09 AM
Denver P. (Obsyden) added a comment.EditedNov 26 2020, 11:13 AM

How can I verify the window manager's keystroke events to confirm this? To clarify, other UI controls in Blender that require dragging (value sliders, pull out menus etc.) are functioning perfectly; other programs like Inkscape and GIMP also function perfectly. The only erroneous system is the Blender node editor.

Robert Guetzkow (rjg) changed the task status from Needs Triage to Needs Information from User.Nov 26 2020, 2:33 PM

I haven't previously debugged/logged/monitored key events for X11, so unfortunately I can't give you proper instructions. Perhaps another developer has an idea.

Denver P. (Obsyden) closed this task as Resolved.Nov 26 2020, 8:59 PM
Denver P. (Obsyden) claimed this task.

New information, found that the mouse was at fault. While monitoring xinput, found that the mouse was continuously pressing and releasing while being dragged - so not a Blender issue, though it is weird that only the node system is affected. Testing with another mouse fixed it - now to fix this mouse!

Robert Guetzkow (rjg) added a comment.Nov 26 2020, 9:52 PM

@Denver P. (Obsyden) Thank you for investigating! Glad you've found the issue.