kivy: dismiss invoice_dialog before delete (fix #6816)
kivy: dismiss invoice_dialog before delete (fix #6816)

spesmilo/electrum,spesmilo/electrum,wakiyamap/electrum-mona,pooler/electrum-ltc,wakiyamap/electrum-mona,pooler/electrum-ltc,wakiyamap/electrum-mona,spesmilo/electrum,pooler/electrum-ltc,pooler/electrum-ltc,spesmilo/electrum,wakiyamap/electrum-mona