On not-us redhat/turbo , if you try to paste a "empty string", mean
you pushdown both left and right buttons of your mouse (a simulated third
mouse button) without really having some characters selected, the vm crashes
with following error message. (you might need to select some characters
in the textfield first, then unselect them, then do the paste).

java: wcsrtombs.c:116 __wcsrtombs: Assertion 'data.outbuf != (unsigned char *) dat' failed.

CAUSE:
looks like the wcstombs() glibc call crashes if you set the third
param to 0, the following normal C program also crashes

    char buf[100];
    wchar_t wcs[100];
    int num_bytes
    num_bytes = wcstombs(buf, wcs, 0);

and we have code in motif's TextFSel.c tries to call wcstombs with
third param is 0.

have a suggested fix which has been confirmed on turbo/redhat ja/zh
version.