When there is more than one line is selected and Inline Search is opened then:

initialize search to the last history (not the selection),
mark on a left ruler the selected region in a different color,
add a mark on a right side of “X of Y” in the same color (indicate that we are running in “scope” mode),
all actions stays in the scope (search, replace),
if Inline Search is disposed scope is removed from the ruler,
if Inline Search stays opened and multi selection is changed then new scope is defined.