EditingSession needs a boolean property called insertMode, so we need
public methods:
public void setInsertMode(boolean f);
public boolean getInsertMode();
EditingSession needs an integer properties callse firstLineDisplayed,
firstPositionDisplayed so we need public methods:
public void setFirstLineDisplayed(int n);
public int getFirstLineDisplayed();
public void setFirstPositionDisplayed(int n);
public int getFirstPositionDisplayed();
Group 3 or 4: need commands called insertmodetoggle, insertmodeset, insertmodeclear
Group 4: need command: C_CURSOR_DOWN_HOME, moves the cursor to the
start of the next line.
Group 4: deleteAt command throws exception if cursor past end of line.
Group 4: deleteBefore command does not delete the first character on a line.