SciTE 3.3.7 - cannot move mouse to left gutter

0.3.17RC2, VBox 4.3.12.

Using SciTE 3.3.7, I can't move mouse into the left gutter, the cursor "jumps" over that space. Please see attached video for what I mean.

This is all that's in debuglog since app launch:
(dll/win32/kernel32/client/proc.c:4038) Current directory: D:\0.3.16and17
(dll/ntdll/ldr/ldrinit.c:1591) We don't support LOAD_CONFIG data yet
(lib/rtl/actctx.c:2309) unknown attr xmlns:asmv3=urn:schemas-microsoft-com:asm.v3
(lib/rtl/actctx.c:2395) unknown element asmv3:application
(lib/rtl/actctx.c:1395) Unsupported yet language attribute ((null))
(lib/rtl/actctx.c:2395) unknown element trustInfo
fixme:(dll/win32/ole32/stubmanager.c:629) No interface for iid