This is a little explanation about those two features added to the 500D and 600D
DIALOG TRICKS... (based on
code from Greg)

From that menu you can enable more settings in photo dialogs opened by camera buttons like ISO and arrows.
ISO button:

When enabled will add Flash exp. comp. to ISO dialog (up or down arrow changes value), and toggle HTP with PLAY button;
WB up button:

When enabled will add Kelvin selection to WB dialog (up or down arrow changes value);
DriveMode left button:

When enabled will add MeteringMode to DriveMode dialog toggable with PLAY button and UP or DOWN arrows;
FocusMode right button:

When enabled will add Focus Pattern selection to FocusMode dialog.
PLAY changes central focus patterns;
UP/DOWN arrows changes vertical patterns;
scrollwheel changes horizontal patterns.
PicStyle down button:

When enabled will open another (user selectable) dialog instead of PicStyle dialog (shown with C-modes enabled);
Options are: Quality, Exp. Comp., Flash Exp. Comp., ALO, OFF (Pic Style)
TO DO:
1)
Add focus pattern selection to Focus dialog2)
Make alternative PicStyle dialog selectable (like set button in C.Fn for example)3) Add max ISO selection for AUTO mode in ISO dialog (with ZoomIn button).
4) Add UniWb to PLAY button when in WB Dialog (it will need to go to LV and back probably for it to work).
5)
Add ALO/HTP toggle with PLAY button in ISO dialog added.