Here is some backgroud -- skip to the next paragraph for the meat of the problem. I have been fighting an issue with the mouse scroll wheel in (KDE based) Linux guests for quite some time now. It seemed to surface for me with the Fedora 22 release (possibly due to the KDE version included there). This issue does not occur in prior versions of the OS (such as Fedora 21), but does occur consistently in every version since (up through the current, Fedora 24). I had written this off to be solely an OS or desktop (KDE) issue, which is why I had not brought it here for help yet. However, I did some additional testing recently which has convinced me that this at least partially lies on the VirtualBox side. I took some time recently to to install a VirtualBox guest OpenSUSE KDE system and it encountered the exact same symptoms as the Fedora system. Then I took the (extensive) time to setup and configure an ArchLinux KDE system, and it too experienced the same symptoms. The final test that led me to post here was to load up a clean Fedora 24 KDE guest system and leave Guest Additions uninstalled temporarily -- this eliminated the symptoms entirely.
Let me explain the problem and how to replicate...
Issue:
On a (KDE) Linux guest system with VirtualBox Guest Additions installed the mouse wheel scroll works erratically in certain applications. Whether scrolling up or down, in an OS based window (such as Konsole or the KDE "start" menus), the scrolling is inconsistent and erratic. It will seem to work correctly for a moment and then will begin to miss input (or misinterpret it), going partially unresponsive and/or scrolling tiny amounts at a time (less than a line worth). The mouse scroll settings are at their OS default of 3 lines per scroll - nothing changed from a default installation. However, when leaving the Guest Additions pacakge uninstalled, the mouse wheel scrolling works perfectly normal across all KDE apps.
Workaround:
The one "workaround" I've found that seems to temporarily cause the scrolling to work correctly is to hover the mouse pointer directly over the scroll bar itself for an affected window (instead of the inner window area) and then scroll while holding the mouse pointer there. When hovering the mouse pointer directly over the window's scroll bar AND simultaneously rolling the mouse wheel, it scrolls the correct amount consistently. Any time the mouse pointer is moved anywhere else in that window the scroll wheel action turns erratic again.
Replication:
This issue is easily reproducible, 100% of the time for me, on two separate host systems (one Windows 7 corporate laptop, and one Windows 10 desktop), using all latest versions of VirtualBox with Guest Additions installed. Here are the steps to replicate:
- Load and update a current copy of Fedora or OpenSUSE with the KDE desktop.
- Perform installation of most current VritualBox Guest Additions and recycle guest system.
- Launch Konsole and run the following command: ls -l /dev
- Within that Konsole window attempt to use the mouse wheel to scroll up through the resulting list of /dev files and observe erratic scrolling activity.
The erratic mouse wheel scrolling can also be observed in the KDE "start" menu, under categories like "Internet" that have enough items to enable a scroll bar. It also seems to occur within apps like Dolphin and the KDE System Settings window. This erratic behavior does not occur in apps like Firefox though.
Again, leaving the Guest Additions package uninstalled completely eliminates this undesired erratic behavior, but obviously leaves important functions like auto-resize guest completely unavailable. These features are critical to my use-case scenario for VirtualBox, so this really is a show stopper for me.
As stated above, this has been tested against every public release of VirtualBox since the behavior initially presented, up through 5.1.2. The log files do not seem to have any relevant information in them, but I have attached the most recent copies anyway for reference. Let me know if anything there's anything else helpful I can provide here.
EDIT: Ok, I'm not seeing any activity on this. These forums are usually very quick to respond. Has anyone tried to replicate this issue at least? I would love it if somebody could at least confirm what I am seeing, so I know I'm not going crazy. Should I have posted this in the "VirtualBox on Windows Hosts" sub instead of in "Linux Guests" maybe? Any help or ideas is greatly appreciated.