just a few thoughts about the subwindows of the nice screenshot:)

Registers:
OK.

Timers:
Timer2 has a completely different layout from Timer1 and Timer2. Homogenize and
place timer counts below each other so they are visible at a glance
TH0 TL0
TH1 TL1
TH2 TL2

(run control subwindow)
should maybe contain (or reserve space for)
step10, step100, step into, step over, step until next branch,
step until next ret(i).


Ports:
OK, but please use lowercase letters for the values -
AB and A8 or D and 0 are very much alike. In lowercase:
ab and a8 or d and 0 this problem does not exist.
(Using lowercase letters might break expectations from
assembler programmers but it is the right thing to do.)

Serial Port:
reserve some space to represent current value as ASCII
and previous values a string.
Separated for SBUF when read and written.
(display non ASCII chars as '.')

IRAM:
This lists uppermost address on top (Registers R0..R7 are listed
the other way round).
IRAM above 0x80 does not seem to be editable.

SFR:
Column headers only show 0 1 2 3 4 5 6 7 and
do not show 8 9 a b c d e f

Disassembly Window:
Please do not (ever) use a proportional font for something
that scolls by or otherwise changes frequently.

Happy Hacking!

Frieder