Unable to place a surface on a sprite using layout-plugins

[oidapala]

ias.conf

Connect a keyboard to the target start weston wtih the specified ias.conf # weston-simple-egl >dev/null & # layoutctrl --set-layout=1

Press the "X" key or "Z" key

Expected: the simple egl should appear on the right of the screen

Observed: nothing happens visually and weston reports :

Jan 16 14:08:37 N20190111-27160 ias-weston-launch[571]: [14:08:37.642] No RBC capable sprite availableKEY_Z
Jan 16 14:08:37 N20190111-27160 ias-weston-launch[571]: [14:08:37.658] IAS ERROR: All sprites already has surface assigned
Jan 16 14:08:37 N20190111-27160 ias-weston-launch[571]: [14:08:37.658] No RBC capable sprite available[14:08:37.658] IAS ERROR: All sprites already has surface assigned
Jan 16 14:08:37 N20190111-27160 ias-weston-launch[571]: [14:08:37.658] No RBC capable sprite available[14:08:37.675] IAS ERROR: All sprites already has surface assigned
Jan 16 14:08:37 N20190111-27160 ias-weston-launch[571]: [14:08:37.675] No RBC capable sprite available[14:08:37.675] IAS ERROR: All sprites already has surface assigned
Jan 16 14:08:37 N20190111-27160 ias-weston-launch[571]: [14:08:37.675] No RBC capable sprite available[14:08:37.692] IAS ERROR: All sprites already has surface assigned
Jan 16 14:08:37 N20190111-27160 ias-weston-launch[571]: [14:08:37.692] No RBC capable sprite available[14:08:37.692] IAS ERROR: All sprites already has surface assigned
Jan 16 14:08:37 N20190111-27160 ias-weston-launch[571]: [14:08:37.692] No RBC capable sprite available[14:08:37.708] IAS ERROR: All sprites already has surface assigned
Jan 16 14:08:37 N20190111-27160 ias-weston-launch[571]: [14:08:37.708] No RBC capable sprite available[14:08:37.709] IAS ERROR: All sprites already has surface assigned

Jan 16 14:08:38 N20190111-27160 ias-weston-launch[571]: [14:08:38.479] No RBC capable sprite availableKEY_X
Jan 16 14:08:38 N20190111-27160 ias-weston-launch[571]: [14:08:38.495] IAS ERROR: All sprites already has surface assigned
Jan 16 14:08:38 N20190111-27160 ias-weston-launch[571]: [14:08:38.495] No RBC capable sprite available[14:08:38.496] IAS ERROR: All sprites already has surface assigned
Jan 16 14:08:38 N20190111-27160 ias-weston-launch[571]: [14:08:38.496] No RBC capable sprite available[14:08:38.512] IAS ERROR: All sprites already has surface assigned
Jan 16 14:08:38 N20190111-27160 ias-weston-launch[571]: [14:08:38.512] No RBC capable sprite available[14:08:38.512] IAS ERROR: All sprites already has surface assigned
Jan 16 14:08:38 N20190111-27160 ias-weston-launch[571]: [14:08:38.512] No RBC capable sprite available[14:08:38.529] IAS ERROR: All sprites already has surface assigned
Jan 16 14:08:38 N20190111-27160 ias-weston-launch[571]: [14:08:38.529] No RBC capable sprite available[14:08:38.529] IAS ERROR: All sprites already has surface assigned
Jan 16 14:08:38 N20190111-27160 ias-weston-launch[571]: [14:08:38.529] No RBC capable sprite available[14:08:38.546] IAS ERROR: All sprites already has surface assigned
Jan 16 14:08:38 N20190111-27160 ias-weston-launch[571]: [14:08:38.546] No RBC capable sprite available[14:08:38.546] IAS ERROR: All sprites already has surface assigned