It would be nice if the debug console had a little help page of itself, to describe the syntax to issue commands (also the nested ones), and a disclaimer that usage can be dangerous.

Maybe add a debug-console-only command like help that shows how to use nested commands and potentially other advanced tricks, and add 'for more information on using this console type XXX'.

See also:
- https://github.com/bitcoin/bitcoin/pull/7783#issuecomment-248274853
- https://github.com/bitcoin/bitcoin/issues/8544#issuecomment-240970925
- #8912 Console command paths cannot be specified correctly with backslashes
#if QT_VERSION < 0x050000
#include <QUrl>
#endif
const int CONSOLE_HISTORY = 50;
const int INITIAL_TRAFFIC_GRAPH_MINS = 30;
const QSize FONT_RANGE(4, 40);
const char fontSizeSettingsKey[] = "consoleFontSize";
const struct {
    const char *url;
    const char *source;
} ICON_MAPPING[] = {
    {"cmd-request", ":/icons/tx_input"},
    {"cmd-reply", ":/icons/tx_output"},
    {"cmd-error", ":/icons/tx_output"},
    {"misc", ":/icons/tx_inout"},
    {nullptr, nullptr}
};
namespace {
const QStringList historyFilter = QStringList()
    << "importprivkey"
    << "importmulti"
    << "signmessagewithprivkey"
    << "signrawtransaction"
    << "walletpassphrase"
    << "walletpassphrasechange"
    << "encryptwallet";
}
/* Object for executing console RPC commands in a separate thread.
*/
class RPCExecutor : public QObject