Paragraph * par_;
/// The position inside the paragraph
lyx::pos_type pos_;
- /// FIXME
+ /**
+ * When the cursor position is i, is the cursor is after the i-th char
+ * or before the i+1-th char ? Normally, these two interpretations are
+ * equivalent, except when the fonts of the i-th and i+1-th char
+ * differ.
+ * We use boundary_ to distinguish between the two options:
+ * If boundary_=true, then the cursor is after the i-th char
+ * and if boundary_=false, then the cursor is before the i+1-th char.
+ *
+ * We currently use the boundary only when the language direction of
+ * the i-th char is different than the one of the i+1-th char.
+ * In this case it is important to distinguish between the two
+ * cursor interpretations, in order to give a reasonable behavior to
+ * the user.
+ */
bool boundary_;
/// the pixel x position
int x_;