Use -xl switch when connecting thru LAN:



One effect of specifying LAN speed being Windows contents are displayed when they are dragged.

Full documentation:

-x <experience>
Changes default bandwidth performance behaviour for RDP5. By
default only theming is enabled, and all other options are dis-
abled (corresponding to modem (56 Kbps)). Setting experience to
b[roadband] enables menu animations and full window dragging.
Setting experience to l[an] will also enable the desktop wallpa-
per. Setting experience to m[odem] disables all (including
themes). Experience can also be a hexidecimal number containing
the flags.