I found it works better then Double-left click.
edit bufftabs.e, replace:
_menu_insert(menu_handle,0,MF_ENABLED,
"&Save "strip_filename(buf_name,'P'),"buff-menu-save","","",'Save 'buf_name);
_menu_insert(menu_handle,1,MF_ENABLED,
"&Close "strip_filename(buf_name,'P'),"buff-menu-close","","",'Close 'buf_name);
with:
_menu_insert(menu_handle,0,MF_ENABLED,
"&Close "strip_filename(buf_name,'P'),"buff-menu-close","","",'Close 'buf_name);
_menu_insert(menu_handle,1,MF_ENABLED,
"&Save "strip_filename(buf_name,'P'),"buff-menu-save","","",'Save 'buf_name);