Hi, the current 802.11 protocols (b\g\n\ac) are designed the way that the client chooses itself which radio AP to use (for apple devices for example signal drop to -75 db is the point)
so the only way for you to make some kind of "roaming wireless network" is to set same SSIDs and make a reject rule(wich drops device from current CAP and device will reconnect itself to better CAP if it finds one) with signal range parameters depending on your wireless signal strength and CAPs locations(start with default one like on your screenshot, it works for all wireless interfaces).
Usually you'll need some wireless signals analyzer to get it right and in the best way but in practice you can do it approximately just measuring signal with your laptop and some software which can scan wifi signals strength and noise,
do not take last statement as advice or guide =)
enabled default rules:
/caps-man access-list
add action=accept allow-signal-out-of-range=10s disabled=no interface=any signal-range=-80..120 ssid-regexp=""
add action=reject allow-signal-out-of-range=10s disabled=no interface=any signal-range=-120..-81 ssid-regexp=""