[Prime] Suggestion for a few easy to implement usability enhancements

[matthiaspaul]

Hi,

Playing with the HP Prime emulator, I identified a few repeating keystroke (or mouse-stroke) sequences which could be simplified in order to reduce finger movement for some frequent actions.

- The backspace button ("<x|") deletes the character to the left of the cursor in the input line. If there are no more characters left to the left of the cursor, pressing the button will have no function at present. The functionality could be improved by switching the function of the button to the behaviour of "DEL" under this condition, that is, start to delete the character on the right side of the cursor (if there is any).
Similar, but less commonly used, the shifted function of the "<x|" button ("DEL") should start to delete characters to the left of the cursor, if there are no more characters left on the right side of the cursor.
So, basically, whenever the "deleting" cursor hits the corresponding edge of the input line, its deletion direction should be reversed until the input line is empty. This would make it easier to edit the input line regardless of cursor position without affecting existing functionality.

- If the backspace button ("<x|") is pressed (shifted or normal) while the input line is completely empty already, it should recall previous contents of the input line and place the cursor at the end of that line (similar to what the HP 20b and HP 30b do in this situation). Again, this would not affect existing functionality at all, just extend behaviour.

- The "Shift" and "Alpha" keys already have some kind of toggle behaviour. This could be extended to a number of other keys as well:

-- Pressing "Home" invokes the "Home" screen.
-- Double-pressing "Home" should invoke "Home settings" (exactly like "Shift"+"Home", but with less finger or mouse travel)
-- While in "Home settings", pressing "Home" again closes the "Home settings" menu (like "ESC").

-- Pressing "CAS" invokes the "CAS" screen.
-- Double-pressing "CAS" should invoke "CAS settings" (exactly like "Shift"+"CAS", but with less finger or mouse travel)
-- While in "CAS settings", pressing "CAS" again closes the "CAS settings" menu (like "ESC").

-- Double-pressing "Apps" should invoke "Info". Pressing it again should switch to the "Apps" view again.

-- Double-pressing "Esc" should invoke "Clear" (perhaps with a pop-up "Are you sure?")

-- Double-pressing "Symb" should invoke "Symb Setup".

- Double-pressing "Plot" should invoke "Plot Setup".

- Double-pressing "Num" should invoke "Num Setup".

- Not sure if double-pressing "Help" and "View" keys should invoke their shifted functions, but otherwise double-pressing them could just close their views again (like "Esc").

- The "Menu/Paste", "Vars/Chars", "Toolbox/Mem" and "C/Unit" keys (normal and shifted) invoke either menus or special functions. When the key gets pressed again, they should close their corresponding menu or application again (like "Esc"). In addition to this, they should also close when one of the other keys is pressed, f.e. while you are in the "Vars" menu, pressing the "Toolbox/Mem" key should close the "Vars" menu and open the "Toolbox" menu, instead of requiring to press "Esc" first. Similar for the other combinations.

These enhancements should be very easy to implement (and they don't get in the way of existing functionality, so noone would need to be retrained or documentation be changed), but they would allow faster navigation via keyboard (and mouse in the emulator). The enhancements are intuitive and easy to memorize, and none of them invokes any "dangerous" functions (perhaps except for "Clear") on a double key press, which is important so that no problems emerge when someone accidently presses a key twice in succession (or because of some impairment).

Greetings,

Matthias