large cursor flickers or disappears

When the cursor is set to a large image it flickers or disappears completely. With nouveau the bug does not happen. Reproduced with nvidia 195 in lucid, 304 in precise, and 331 in trusty running compiz, metacity, and gnome-shell. It seems to be less severe under metacity: the cursor still flickers but doesn't actually disappear as often. It also seems to be less severe in trusty than in precise, but still flickers badly and occasionally disappears. Upgrading to nvidia 331 in precise didn't change anything, so I think some other component is also related.

Disabling HWCursor in xorg.conf doesn't change anything under metacity, but under gnome-shell and compiz it makes the cursor (any size, including the default) flicker and disappear all the time.

ktuberling is affected by this bug. It uses Qt's QWidget::setCursor() to replace the cursor with an image of the item you clicked on. Smaller items work and larger ones flicker or disappear. With nouveau it works as expected, there is no flickering.

Attached is a trivial Qt program that demonstrates the bug using QWidget::setCursor(). On my system (GT218 [GeForce 210]) the bug appears with cursors larger than 64x64 px. I don't know whether that number is hardware-dependent.

Can I provide any other useful information?