AbsoluteTelnet has strong scrollback capability. You can access history as far back as you like, much further than traditional telnet applications. The scroll bar on the right side of the terminal window is enabled by default. It can be toggled in the appearance options menu.
Normal text selections can be made using the left mouse button to click and drag the selection. Additionally, rectangular selections can be made by holding down the alt key prior to making the selection.
If the mouse moves out of the terminal window during a drag operation, the terminal window will automatically scroll (either up or down) to allow selection of sections that span off the screen.