[RFC PATCH v2 3/3] doc: describe new difftool.tabbed feature

[Nicholas Guriev <nicholas@guriev.su>]

And related the `--tabbed` command line option and the
GIT_DIFFTOOL_TABBED environment variable.
---
 Documentation/config/difftool.txt |  6 ++++++
 Documentation/git-difftool.txt    | 19 +++++++++++++++----
 Documentation/git.txt             |  4 ++++
 3 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/Documentation/config/difftool.txt b/Documentation/config/difftool.txt
index 6762594480..ac609aee66 100644
--- a/Documentation/config/difftool.txt
+++ b/Documentation/config/difftool.txt
@@ -12,3 +12,9 @@ difftool.<tool>.cmd::
 
 difftool.prompt::
 	Prompt before each invocation of the diff tool.
+
+difftool.tabbed::
+	Show compared files in different tabs using single invocation of
+	the diff tool. Must be a boolean value. Only the following tools
+	are currently supported: vimdiff and related, meld. Tools with
+	overridden command line will ignore this configuration variable.
diff --git a/Documentation/git-difftool.txt b/Documentation/git-difftool.txt
index 484c485fd0..1b7a5345ad 100644
--- a/Documentation/git-difftool.txt
+++ b/Documentation/git-difftool.txt
@@ -69,6 +69,13 @@ with custom merge tool commands and has the same value as `$MERGED`.
 --tool-help::
 	Print a list of diff tools that may be used with `--tool`.
 
+--[no-]tabbed::
+	Open compared files in different tabs using single invocation
+	of the diff tool. This overrides configuration or environment.
+	Currently, only the following tools are supported: vimdiff and
+	related, meld. Tools with overridden command line will ignore
+	this option.
+
 --[no-]symlinks::
 	'git difftool''s default behavior is create symlinks to the
 	working tree when run in `--dir-diff` mode and the right-hand
@@ -95,10 +102,11 @@ instead.  `--no-symlinks` is the default on Windows.
 	`diff.tool`, `merge.tool` until a tool is found.
 
 --[no-]trust-exit-code::
-	'git-difftool' invokes a diff tool individually on each file.
-	Errors reported by the diff tool are ignored by default.
-	Use `--trust-exit-code` to make 'git-difftool' exit when an
-	invoked diff tool returns a non-zero exit code.
+	'git-difftool' invokes a diff tool individually on each file
+	unless tabbed mode is active. Errors reported by the diff tool
+	are ignored by default. Use `--trust-exit-code` to make
+	'git-difftool' exit immediately when an invoked diff tool
+	returns a non-zero exit code.
 +
 'git-difftool' will forward the exit code of the invoked tool when
 `--trust-exit-code` is used.
@@ -128,6 +136,9 @@ See the `--tool=<tool>` option above for more details.
 difftool.prompt::
 	Prompt before each invocation of the diff tool.
 
+difftool.tabbed::
+	Configure default value of the `--tabbed` option. See above.
+
 difftool.trustExitCode::
 	Exit difftool if the invoked diff tool returns a non-zero exit status.
 +
diff --git a/Documentation/git.txt b/Documentation/git.txt
index a6d4ad0818..d7cd6650c9 100644
--- a/Documentation/git.txt
+++ b/Documentation/git.txt
@@ -583,6 +583,10 @@ For each path `GIT_EXTERNAL_DIFF` is called, two environment variables,
 `GIT_DIFF_PATH_TOTAL`::
 	The total number of paths.
 
+`GIT_DIFFTOOL_TABBED`::
+	Run the diff tool in tabbed mode opening all compared files
+	together. It must contain a boolean value.
+
 other
 ~~~~~
 `GIT_MERGE_VERBOSITY`::
-- 
2.27.0