Use following key shortcuts, as they help in faster code development
1) select the code line or lines, then Ctrl + Alt + Up Arrow Key or Ctrl + Alt + Down Arrow Key
— copy the selected line or lines of code on upside/downside of the selected line or lines
2) Ctrl + O
— opens the window with all variables , functions and controls in current .mxml or .as file
3) Ctrl + Shift +R
— opens the window with list of all files of all open projects in the workspace of Flex builder
— very useful if you remember the filename of the file which you want to open.
4) Ctrl + Shift +F
— opens the search window and search throught files of all open projects in the workspace of Flex builder
Enjoy great coding of Flex !!I will post some more in future. You can also find key assist in Flex builder by Ctrl+Shift+L.