All current models of Palm's handheld computers and smartphones feature
a large round scroll button, also known as the D-pad.
This button lets you use the computer with just one hand, without having
to tap the screen with the stylus.
Planisphere makes extensive use of the D-pad.
On the main screen, press the D-pad up, down, left and right to
zoom and scroll the chart. Press the center of the D-pad
once to switch between zooming and scrolling, twice to
activate the command icons in the upper right corner of the screen.
Press the center yet again to perform the command of the currently
highlighted icon.
On the
Star Finder
screen, press the D-pad up and down to page through the constellations,
left and right to cycle through the named stars of a constellation.
You can also use the D-pad to activate the menu
if your handheld computer does not have a dedicated menu button.
Press and hold the center of the D-pad until the menu appears.
(This can be a little tricky on the early Tungsten models, where holding
too long would take you out of the program entirely; with practice you'll
learn to let go just in time.) Once the menu is active, you can navigate
it using the D-pad.
If you have a smartphone with a full keyboard, you can do
menu shortcuts without having to go through the menu at all.
Merely typing the letter of a shortcut will perform its command.
(The space bar and the return key also do useful things.)