newline: support PROMPT_ON_NEWLINE

The newline segment will now show ├─ when using
`POWERLEVEL9K_PROMPT_ON_NEWLINE`

Note: This can be overridden via `POWERLEVEL9K_MULTILINE_FIRST_PROMPT_PREFIX`

functions/icons.zsh

@@ -39,8 +39,9 @@ case $POWERLEVEL9K_MODE in
       FAIL_ICON                      $'\u2718'              # ✘
       SYMFONY_ICON                   'SF'
       NODE_ICON                      $'\u2B22'              # ⬢
-      MULTILINE_FIRST_PROMPT_PREFIX  $'\u256D'$'\U2500'
-      MULTILINE_SECOND_PROMPT_PREFIX $'\u2570'$'\U2500 '
+      MULTILINE_FIRST_PROMPT_PREFIX  $'\u256D'$'\U2500'     # ╭─
+      MULTILINE_NEWLINE_PROMPT_PREFIX  $'\u251C'$'\U2500'   # ├─
+      MULTILINE_SECOND_PROMPT_PREFIX $'\u2570'$'\U2500 '    # ╰─
       APPLE_ICON                     $'\uE26E'              # 
       WINDOWS_ICON                   $'\uE26F'              # 
       FREEBSD_ICON                   $'\U1F608 '            # 😈
@@ -111,6 +112,7 @@ case $POWERLEVEL9K_MODE in
       SYMFONY_ICON                   'SF'
       NODE_ICON                      $'\u2B22'              # ⬢
       MULTILINE_FIRST_PROMPT_PREFIX  $'\u256D'$'\U2500'     # ╭─
+      MULTILINE_NEWLINE_PROMPT_PREFIX  $'\u251C'$'\U2500'   # ├─
       MULTILINE_SECOND_PROMPT_PREFIX $'\u2570'$'\U2500 '    # ╰─
       APPLE_ICON                     $'\uF179'              # 
       WINDOWS_ICON                   $'\uF17A'              # 
@@ -178,6 +180,7 @@ case $POWERLEVEL9K_MODE in
       SYMFONY_ICON                   $'\uE757'              # 
       NODE_ICON                      $'\uE617 '             # 
       MULTILINE_FIRST_PROMPT_PREFIX  $'\u256D'$'\U2500'     # ╭─
+      MULTILINE_NEWLINE_PROMPT_PREFIX  $'\u251C'$'\U2500'   # ├─
       MULTILINE_SECOND_PROMPT_PREFIX $'\u2570'$'\U2500 '    # ╰─
       APPLE_ICON                     $'\uF179'              # 
       WINDOWS_ICON                   $'\uF17A'              # 
@@ -244,8 +247,9 @@ case $POWERLEVEL9K_MODE in
       FAIL_ICON                      $'\u2718'              # ✘
       SYMFONY_ICON                   'SF'
       NODE_ICON                      $'\u2B22'              # ⬢
-      MULTILINE_FIRST_PROMPT_PREFIX  $'\u256D'$'\u2500'
-      MULTILINE_SECOND_PROMPT_PREFIX $'\u2570'$'\u2500 '
+      MULTILINE_FIRST_PROMPT_PREFIX  $'\u256D'$'\U2500'     # ╭─
+      MULTILINE_NEWLINE_PROMPT_PREFIX  $'\u251C'$'\U2500'   # ├─
+      MULTILINE_SECOND_PROMPT_PREFIX $'\u2570'$'\U2500 '    # ╰─
       APPLE_ICON                     'OSX'
       WINDOWS_ICON                   'WIN'
       FREEBSD_ICON                   'BSD'

powerlevel9k.zsh-theme

@@ -339,14 +339,18 @@ prompt_background_jobs() {
 
 # A newline in your prompt, so you can segments on multiple lines.
 prompt_newline() {
-  local lws
+  local lws newline
   [[ "$1" == "right" ]] && return
+  newline=$'\n'
   lws=$POWERLEVEL9K_WHITESPACE_BETWEEN_LEFT_SEGMENTS
+  if [[ "$POWERLEVEL9K_PROMPT_ON_NEWLINE" == true ]]; then
+    newline="${newline}$(print_icon 'MULTILINE_NEWLINE_PROMPT_PREFIX')"
+  fi
   POWERLEVEL9K_WHITESPACE_BETWEEN_LEFT_SEGMENTS=
   "$1_prompt_segment" \
     "$0" \
     "$2" \
-    "NONE" "NONE" $'\n'
+    "NONE" "NONE" "${newline}"
   POWERLEVEL9K_WHITESPACE_BETWEEN_LEFT_SEGMENTS=$lws
 }