I use the latest SVN build of DOSBox (r4337) with D-Fend Reloaded frontend.
I set the Window resolution and Fullscreen resolution to Original.
I start with Fullscreen.
I also use Double Buffering.
My render is Surface.
My Video card is set to vgaonly. No scaling and 0 frameskip.
My emulation core is set to dynamic.
My CPU Type is Auto.
My CPU cycles is Auto.

When I play "Titus The Fox" in the first level, sometimes some characters (including the Fox) disappear and reappear very quickly (vibrate). Only clear in the end of the level.

Is this a bug?
Please investigate and tell me.
Please try to fix if it is a bug.
Thank you very much.