Hi,

This patch can make the disassembly/memory window accept symbol name in
spin Button.

Here is what it does:
- When input a available symbol name at fromBox, the window would
display the disassembly/memory of this symbol. The fromBox/fromSpin
would be set the start address of this symbol and the toBox/toSpin would
be set the end address of this symbol.
- When input a available symbol name at toBox, it would do as same as
when input at fromBox.
- When input a unavailable symbol name, the fromBox/fromSpin or
toBox/toSpin would be reset to the lastKnownFrom or lastKnownTo.

Any suggestions are welcomed.

Pearly Zhao