selecting previous tool?

[weipai]

hi, i'm looking for a way to select the previous tool via scripts (if that's at all possible), like how when you hold down a tool hot key (R for rotate, B for brush and etc.) for long enough and let go it goes back to whatever the last tool was before you pushed the hot key. i don't know how long the delay is, feels like half a second or so, and if you don't hold it long enough or just tab the hot key quickly it stays on its tool obviously. script listener only shows the scripts for selecting whichever tool, but not how photoshop remembers what the previous tool was, so i don't know if this behaviour can be scripted, but i'm sure someone here knows better. appreciate any help or insight