Escape sequence to set cursor hollow?

Question

I'm using xterm. If the xterm window loses the focus the text cursor becomes hollow. I want to use a hollow cursor as cursor form when vim switches from insert into normal mode. Therefore I need the escape sequence to change the cursor from block into hollow.

Answer 1

xterm does not do that. It (currently) provides distinguishable combinations of these (using the DECSCUSR control sequence):

• (solid) block
• underline (rather than block)
• vertical bar (rather than block or underline)
• blinking (combined with any of the above)

Empty blocks denote, as you have observed, the fact that xterm no longer has the focus.

There is no control sequence which will produce an empty block.