#1889 Add support for automatically previewing messages based on the cursor position

doc/ale.txt

@@ -527,12 +527,13 @@ circumstances.
 ALE will report problems with your code in the following ways, listed with
 their relevant options.
 
-* By updating loclist. (On by default)       - |g:ale_set_loclist|
-* By updating quickfix. (Off by default)     - |g:ale_set_quickfix|
-* By setting error highlights.               - |g:ale_set_highlights|
-* By creating signs in the sign column.      - |g:ale_set_signs|
-* By echoing messages based on your cursor.  - |g:ale_echo_cursor|
-* By showing balloons for your mouse cursor  - |g:ale_set_balloons|
+* By updating loclist. (On by default)             - |g:ale_set_loclist|
+* By updating quickfix. (Off by default)           - |g:ale_set_quickfix|
+* By setting error highlights.                     - |g:ale_set_highlights|
+* By creating signs in the sign column.            - |g:ale_set_signs|
+* By echoing messages based on your cursor.        - |g:ale_echo_cursor|
+* By displaying the preview based on your cursor.  - |g:ale_cursor_detail|
+* By showing balloons for your mouse cursor        - |g:ale_set_balloons|
 
 Please consult the documentation for each option, which can reveal some other
 ways of tweaking the behaviour of each way of displaying problems. You can
@@ -805,6 +806,20 @@ g:ale_change_sign_column_color                 *g:ale_change_sign_column_color*
   windows.
 
 
+g:ale_close_preview_on_insert                   *g:ale_close_preview_on_insert*
+
+  Type: |Number|
+  Default: `0`
+
+  When this option is set to `1`, ALE's |preview-window| will be automatically
+  closed upon entering Insert Mode. This option can be used in combination
+  with |g:ale_cursor_detail| for automatically displaying the preview window
+  on problem lines, and automatically closing it again when editing text.
+
+  This setting must be set to `1` before ALE is loaded for this behavior
+  to be enabled. See |ale-lint-settings-on-startup|.
+
+
 g:ale_command_wrapper                                   *g:ale_command_wrapper*
                                                         *b:ale_command_wrapper*
   Type: |String|
@@ -893,6 +908,27 @@ g:ale_completion_max_suggestions             *g:ale_completion_max_suggestions*
   Adjust this option as needed, depending on the complexity of your codebase
   and your available processing power.
 
+g:ale_cursor_detail                                       *g:ale_cursor_detail*
+
+  Type: |Number|
+  Default: `0`
+
+  When this option is set to `1`, ALE's |preview-window| will be automatically
+  opened when the cursor moves onto lines with problems. ALE will search for
+  problems using the same logic that |g:ale_echo_cursor| uses. The preview
+  window will be closed automatically when you move away from the line.
+
+  Messages are only displayed after a short delay. See |g:ale_echo_delay|.
+
+  The preview window is opened without stealing focus, which means your cursor
+  will stay in the same buffer as it currently is.
+
+  The preview window can be closed automatically upon entering Insert mode
+  by setting |g:ale_close_preview_on_insert| to `1`.
+
+  Either this setting or |g:ale_echo_cursor| must be set to `1` before ALE is
+  loaded for messages to be displayed. See |ale-lint-settings-on-startup|.
+
 
 g:ale_echo_cursor                                           *g:ale_echo_cursor*
 
@@ -903,11 +939,14 @@ g:ale_echo_cursor                                           *g:ale_echo_cursor*
   cursor is near a warning or error. ALE will attempt to find the warning or
   error at a column nearest to the cursor when the cursor is resting on a line
   which contains a warning or error. This option can be set to `0` to disable
-  this behaviour.
-  The format of the message can be customizable in |g:ale_echo_msg_format|.
+  this behavior.
 
-  You should set this setting once before ALE is loaded, and restart Vim if
-  you want to change your preferences. See |ale-lint-settings-on-startup|.
+  Messages are only displayed after a short delay. See |g:ale_echo_delay|.
+
+  The format of the message can be customized with |g:ale_echo_msg_format|.
+
+  Either this setting or |g:ale_cursor_detail| must be set to `1` before ALE
+  is loaded for messages to be displayed. See |ale-lint-settings-on-startup|.
 
 
 g:ale_echo_delay                                             *g:ale_echo_delay*
@@ -916,7 +955,7 @@ g:ale_echo_delay                                             *g:ale_echo_delay*
   Default: `10`
 
   Given any integer, this option controls the number of milliseconds before
-  ALE will echo a message for a problem near the cursor.
+  ALE will echo or preview a message for a problem near the cursor.
 
   The value can be increased to decrease the amount of processing ALE will do
   for files displaying a large number of problems.