@jonasschnelli wrote in #14979:
> #14573 broke < Qt5.6 compatibility due to calling the lambda version of `addAction` that was added in Qt5.6.

We currently [support](https://github.com/bitcoin/bitcoin/blob/master/doc/dependencies.md) QT >=5.2, but hardly anyone tests with that. If we make one of the Travis machines use it, we should have a better change of catching this.

See also discussion about minimum QT version in #13478 
{
        auto locked_chain = m_wallet.chain().lock(true );
        if (!locked_chain) return false;
        TRY_LOCK(m_wallet.cs_wallet, locked_wallet);
        if (!locked_wallet) {
            return false;
        }
        balances = getBalances();
        num_blocks = locked_chain->getHeight().get_value_or(-1);
        return true;
    }
    CAmount getBalance() override { return m_wallet.GetBalance(); }
    CAmount getAvailableBalance(const CCoinControl& coin_control) override
    {
        return m_wallet.GetAvailableBalance(&coin_control);
    }
    isminetype txinIsMine(const CTxIn& txin) override
    {
        auto locked_chain = m_wallet.chain().lock();
        LOCK(m_wallet.cs_wallet);
        return m_wallet.IsMine(txin);
    }
    isminetype txoutIsMine(const CTxOut& txout) override
    {
        auto locked_chain = m_wallet.chain().lock();
        LOCK(m_wallet.cs_wallet);
        return m_wallet.IsMine(txout);
    }
    CAmount getDebit(const CTxIn& txin, isminefilter filter) override