How to prevent flicker on geoviews WMTS? or block events until WMTS has been loaded?

[andhuang-CLGX]

I think it's because WMTS is a non-blocking process so the DynamicMap updates before the data has been retrieved which causes a second of an empty canvas.

import geoviews as gv
gv.extension('bokeh')

def plot_tiles(value):
    return gv.WMTS(value)

options = [
    "https://nowcoast.noaa.gov/arcgis/rest/services/nowcoast/analysis_meteohydro_sfc_rtma_time/MapServer/export?transparent=true&format=png8&layers=show%3A7&bboxSR=3857&imageSR=3857&size=256,256&f=image&time=1626901200000&bbox={XMIN},{YMIN},{XMAX},{YMAX}",
    "https://nowcoast.noaa.gov/arcgis/rest/services/nowcoast/analysis_meteohydro_sfc_qpe_time/MapServer/export?transparent=true&format=png8&layers=show%3A7&bboxSR=3857&imageSR=3857&size=256,256&f=image&time=1626901201000&bbox={XMIN},{YMIN},{XMAX},{YMAX}"
]
select = pn.widgets.Select(options=options)
tiles_dmap = gv.DynamicMap(plot_tiles, streams=[select.param.value])
pn.Column(select, tiles_dmap)

[ahuang11]

Hack shown here:
#698