add: WMSetButtonEnabled(panel->okB, WMGetListNumberOfRows(panel->gcolL) > 1);
context: gradDeleteCallback(WMWidget *w, void *data){    TexturePanel *panel = (TexturePanel*)data;    WMListItem *item;    int row;    row = WMGetListSelectedItemRow(panel->gcolL);    if (row < 0)	return;    item = WMGetListItem(panel->gcolL, row);    free(item->clientData);    WMRemoveListItem(panel->gcolL, row);    WMSelectListItem(panel->gcolL, row - 1);    updateGradButtons(panel);    gradClickCallback(panel->gcolL, panel);}