For example, the GNOME 3 desktop environment includes a "Show location of the [mouse] pointer" option in the Keyboard and Mouse section of the Tweak Tool (gnome-extra/gnome-tweak-tool). This option will enable a ripple effect to be displayed around the mouse when either the right or left Ctrl key is pressed. This mouse locator handle conflicts with the virtual machine's handle on the right Ctrl key. Disabling this setting (via switching the rocker switch to Off in the Tweak Tool interface) should fix the problem by re-assigning the right Ctrl key as the handle for the host key within the virtual machine.