diff --git a/src/testdir/dumps/Test_diff_overlapped_3.40.dump b/src/testdir/dumps/Test_diff_overlapped_3.40.dump
new file mode 100644
index 0000000..4307cfb
--- /dev/null
+++ b/src/testdir/dumps/Test_diff_overlapped_3.40.dump
@@ -0,0 +1,20 @@
+| +0#0000e05#a8a8a8255@1|f+0#0000000#ffffff0|o@1| @19||+1&&| +0#0000e05#a8a8a8255@1|f+0#0000000#ffffff0|o@1| @18||+1&&| +0#0000e05#a8a8a8255@1|f+0#0000000#ffffff0|o@1| @18
+| +0#0000e05#a8a8a8255@1|a+2#0000000#ff404010| +0&#ffd7ff255@21||+1&#ffffff0| +0#0000e05#a8a8a8255@1|w+2#0000000#ff404010| +0&#ffd7ff255@20||+1&#ffffff0| +0#0000e05#a8a8a8255@1|1+2#0000000#ff404010| +0&#ffd7ff255@20
+| +0#0000e05#a8a8a8255@1|b+2#0000000#ff404010| +0&#ffd7ff255@21||+1&#ffffff0| +0#0000e05#a8a8a8255@1|x+2#0000000#ff404010| +0&#ffd7ff255@20||+1&#ffffff0| +0#0000e05#a8a8a8255@1|a+2#0000000#ff404010| +0&#ffd7ff255@20
+| +0#0000e05#a8a8a8255@1|c+2#0000000#ff404010| +0&#ffd7ff255@21||+1&#ffffff0| +0#0000e05#a8a8a8255@1|y+2#0000000#ff404010| +0&#ffd7ff255@20||+1&#ffffff0| +0#0000e05#a8a8a8255@1|b+2#0000000#ff404010| +0&#ffd7ff255@20
+| +0#0000e05#a8a8a8255@1|-+0#4040ff13#afffff255@22||+1#0000000#ffffff0| +0#0000e05#a8a8a8255@1|z+2#0000000#ff404010| +0&#ffd7ff255@20||+1&#ffffff0| +0#0000e05#a8a8a8255@1|2+2#0000000#ff404010| +0&#ffd7ff255@20
+| +0#0000e05#a8a8a8255@1|b+0#0000000#ffffff0|a|r| @19||+1&&| +0#0000e05#a8a8a8255@1|b+0#0000000#ffffff0|a|r| @18||+1&&| +0#0000e05#a8a8a8255@1|b+0#0000000#ffffff0|a|r| @18
+|~+0#4040ff13&| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|~| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|~| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|~| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|~| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|~| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|~| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|~| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|~| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|~| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|~| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|~| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|X+3#0000000&|d|i|f|i|l|e|1| @4|1|,|1| @5|A|l@1| |X+1&&|d|i|f|i|l|e|2| @3|1|,|1| @5|A|l@1| |X|d|i|f|i|l|e|3| @3|1|,|1| @5|A|l@1
+|:+0&&> @73
diff --git a/src/testdir/dumps/Test_diff_overlapped_3.41.dump b/src/testdir/dumps/Test_diff_overlapped_3.41.dump
new file mode 100644
index 0000000..658c09f
--- /dev/null
+++ b/src/testdir/dumps/Test_diff_overlapped_3.41.dump
@@ -0,0 +1,20 @@
+| +0#0000e05#a8a8a8255@1|f+0#0000000#ffffff0|o@1| @19||+1&&| +0#0000e05#a8a8a8255@1|f+0#0000000#ffffff0|o@1| @18||+1&&| +0#0000e05#a8a8a8255@1|f+0#0000000#ffffff0|o@1| @18
+| +0#0000e05#a8a8a8255@1|a+2#0000000#ff404010| +0&#ffd7ff255@21||+1&#ffffff0| +0#0000e05#a8a8a8255@1|w+2#0000000#ff404010| +0&#ffd7ff255@20||+1&#ffffff0| +0#0000e05#a8a8a8255@1|1+2#0000000#ff404010| +0&#ffd7ff255@20
+| +0#0000e05#a8a8a8255@1|b+2#0000000#ff404010| +0&#ffd7ff255@21||+1&#ffffff0| +0#0000e05#a8a8a8255@1|x+2#0000000#ff404010| +0&#ffd7ff255@20||+1&#ffffff0| +0#0000e05#a8a8a8255@1|a+2#0000000#ff404010| +0&#ffd7ff255@20
+| +0#0000e05#a8a8a8255@1|c+2#0000000#ff404010| +0&#ffd7ff255@21||+1&#ffffff0| +0#0000e05#a8a8a8255@1|y+2#0000000#ff404010| +0&#ffd7ff255@20||+1&#ffffff0| +0#0000e05#a8a8a8255@1|b+2#0000000#ff404010| +0&#ffd7ff255@20
+| +0#0000e05#a8a8a8255@1|d+2#0000000#ff404010| +0&#ffd7ff255@21||+1&#ffffff0| +0#0000e05#a8a8a8255@1|z+2#0000000#ff404010| +0&#ffd7ff255@20||+1&#ffffff0| +0#0000e05#a8a8a8255@1|2+2#0000000#ff404010| +0&#ffd7ff255@20
+| +0#0000e05#a8a8a8255@1|-+0#4040ff13#afffff255@22||+1#0000000#ffffff0| +0#0000e05#a8a8a8255@1|u+2#0000000#ff404010| +0&#ffd7ff255@20||+1&#ffffff0| +0#0000e05#a8a8a8255@1|d+2#0000000#ff404010| +0&#ffd7ff255@20
+| +0#0000e05#a8a8a8255@1|b+0#0000000#ffffff0|a|r| @19||+1&&| +0#0000e05#a8a8a8255@1|b+0#0000000#ffffff0|a|r| @18||+1&&| +0#0000e05#a8a8a8255@1|b+0#0000000#ffffff0|a|r| @18
+|~+0#4040ff13&| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|~| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|~| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|~| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|~| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|~| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|~| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|~| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|~| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|~| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|~| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|X+3#0000000&|d|i|f|i|l|e|1| @4|1|,|1| @5|A|l@1| |X+1&&|d|i|f|i|l|e|2| @3|1|,|1| @5|A|l@1| |X|d|i|f|i|l|e|3| @3|1|,|1| @5|A|l@1
+|:+0&&> @73
diff --git a/src/testdir/dumps/Test_diff_overlapped_3.42.dump b/src/testdir/dumps/Test_diff_overlapped_3.42.dump
new file mode 100644
index 0000000..2e93570
--- /dev/null
+++ b/src/testdir/dumps/Test_diff_overlapped_3.42.dump
@@ -0,0 +1,20 @@
+| +0#0000e05#a8a8a8255@1|f+0#0000000#ffffff0|o@1| @19||+1&&| +0#0000e05#a8a8a8255@1|f+0#0000000#ffffff0|o@1| @18||+1&&| +0#0000e05#a8a8a8255@1|f+0#0000000#ffffff0|o@1| @18
+| +0#0000e05#a8a8a8255@1|a+2#0000000#ff404010| +0&#ffd7ff255@21||+1&#ffffff0| +0#0000e05#a8a8a8255@1|w+2#0000000#ff404010| +0&#ffd7ff255@20||+1&#ffffff0| +0#0000e05#a8a8a8255@1|1+2#0000000#ff404010| +0&#ffd7ff255@20
+| +0#0000e05#a8a8a8255@1|b+2#0000000#ff404010| +0&#ffd7ff255@21||+1&#ffffff0| +0#0000e05#a8a8a8255@1|x+2#0000000#ff404010| +0&#ffd7ff255@20||+1&#ffffff0| +0#0000e05#a8a8a8255@1|b+2#0000000#ff404010| +0&#ffd7ff255@20
+| +0#0000e05#a8a8a8255@1|c+2#0000000#ff404010| +0&#ffd7ff255@21||+1&#ffffff0| +0#0000e05#a8a8a8255@1|y+2#0000000#ff404010| +0&#ffd7ff255@20||+1&#ffffff0| +0#0000e05#a8a8a8255@1|2+2#0000000#ff404010| +0&#ffd7ff255@20
+| +0#0000e05#a8a8a8255@1|d+2#0000000#ff404010| +0&#ffd7ff255@21||+1&#ffffff0| +0#0000e05#a8a8a8255@1|z+2#0000000#ff404010| +0&#ffd7ff255@20||+1&#ffffff0| +0#0000e05#a8a8a8255@1|3+2#0000000#ff404010| +0&#ffd7ff255@20
+| +0#0000e05#a8a8a8255@1|e+2#0000000#ff404010| +0&#ffd7ff255@21||+1&#ffffff0| +0#0000e05#a8a8a8255@1|e+2#0000000#ff404010| +0&#ffd7ff255@20||+1&#ffffff0| +0#0000e05#a8a8a8255@1|d+2#0000000#ff404010| +0&#ffd7ff255@20
+| +0#0000e05#a8a8a8255@1|f+2#0000000#ff404010| +0&#ffd7ff255@21||+1&#ffffff0| +0#0000e05#a8a8a8255@1|u+2#0000000#ff404010| +0&#ffd7ff255@20||+1&#ffffff0| +0#0000e05#a8a8a8255@1|4+2#0000000#ff404010| +0&#ffd7ff255@20
+| +0#0000e05#a8a8a8255@1|-+0#4040ff13#afffff255@22||+1#0000000#ffffff0| +0#0000e05#a8a8a8255@1|-+0#4040ff13#afffff255@21||+1#0000000#ffffff0| +0#0000e05#a8a8a8255@1|f+0#0000000#5fd7ff255| @20
+| +0#0000e05#a8a8a8255@1|b+0#0000000#ffffff0|a|r| @19||+1&&| +0#0000e05#a8a8a8255@1|b+0#0000000#ffffff0|a|r| @18||+1&&| +0#0000e05#a8a8a8255@1|b+0#0000000#ffffff0|a|r| @18
+|~+0#4040ff13&| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|~| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|~| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|~| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|~| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|~| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|~| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|~| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|~| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|X+3#0000000&|d|i|f|i|l|e|1| @4|1|,|1| @5|A|l@1| |X+1&&|d|i|f|i|l|e|2| @3|1|,|1| @5|A|l@1| |X|d|i|f|i|l|e|3| @3|1|,|1| @5|A|l@1
+|:+0&&> @73
diff --git a/src/testdir/dumps/Test_diff_overlapped_3.43.dump b/src/testdir/dumps/Test_diff_overlapped_3.43.dump
new file mode 100644
index 0000000..f9f75e8
--- /dev/null
+++ b/src/testdir/dumps/Test_diff_overlapped_3.43.dump
@@ -0,0 +1,20 @@
+| +0#0000e05#a8a8a8255@1|f+0#0000000#ffffff0|o@1| @19||+1&&| +0#0000e05#a8a8a8255@1|f+0#0000000#ffffff0|o@1| @18||+1&&| +0#0000e05#a8a8a8255@1|f+0#0000000#ffffff0|o@1| @18
+| +0#0000e05#a8a8a8255@1|a+2#0000000#ff404010| +0&#ffd7ff255@21||+1&#ffffff0| +0#0000e05#a8a8a8255@1|x+2#0000000#ff404010| +0&#ffd7ff255@20||+1&#ffffff0| +0#0000e05#a8a8a8255@1|1+2#0000000#ff404010| +0&#ffd7ff255@20
+| +0#0000e05#a8a8a8255@1|b+2#0000000#ff404010| +0&#ffd7ff255@21||+1&#ffffff0| +0#0000e05#a8a8a8255@1|y+2#0000000#ff404010| +0&#ffd7ff255@20||+1&#ffffff0| +0#0000e05#a8a8a8255@1|a+2#0000000#ff404010| +0&#ffd7ff255@20
+| +0#0000e05#a8a8a8255@1|b+0#0000000#ffffff0|a|r| @19||+1&&| +0#0000e05#a8a8a8255@1|b+0#0000000#ffffff0|a|r| @18||+1&&| +0#0000e05#a8a8a8255@1|b+0#0000000#ffffff0|a|r| @18
+|~+0#4040ff13&| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|~| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|~| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|~| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|~| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|~| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|~| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|~| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|~| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|~| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|~| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|~| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|~| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|~| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|X+3#0000000&|d|i|f|i|l|e|1| @4|1|,|1| @5|A|l@1| |X+1&&|d|i|f|i|l|e|2| @3|1|,|1| @5|A|l@1| |X|d|i|f|i|l|e|3| @3|1|,|1| @5|A|l@1
+|:+0&&> @73
diff --git a/src/testdir/dumps/Test_diff_overlapped_3.44.dump b/src/testdir/dumps/Test_diff_overlapped_3.44.dump
new file mode 100644
index 0000000..64780a4
--- /dev/null
+++ b/src/testdir/dumps/Test_diff_overlapped_3.44.dump
@@ -0,0 +1,20 @@
+| +0#0000e05#a8a8a8255@1|f+0#0000000#ffffff0|o@1| @19||+1&&| +0#0000e05#a8a8a8255@1|f+0#0000000#ffffff0|o@1| @18||+1&&| +0#0000e05#a8a8a8255@1|f+0#0000000#ffffff0|o@1| @18
+| +0#0000e05#a8a8a8255@1|a+2#0000000#ff404010| +0&#ffd7ff255@21||+1&#ffffff0| +0#0000e05#a8a8a8255@1|w+2#0000000#ff404010| +0&#ffd7ff255@20||+1&#ffffff0| +0#0000e05#a8a8a8255@1|1+2#0000000#ff404010| +0&#ffd7ff255@20
+| +0#0000e05#a8a8a8255@1|b+2#0000000#ff404010| +0&#ffd7ff255@21||+1&#ffffff0| +0#0000e05#a8a8a8255@1|x+2#0000000#ff404010| +0&#ffd7ff255@20||+1&#ffffff0| +0#0000e05#a8a8a8255@1|a+2#0000000#ff404010| +0&#ffd7ff255@20
+| +0#0000e05#a8a8a8255@1|c+2#0000000#ff404010| +0&#ffd7ff255@21||+1&#ffffff0| +0#0000e05#a8a8a8255@1|y+2#0000000#ff404010| +0&#ffd7ff255@20||+1&#ffffff0| +0#0000e05#a8a8a8255@1|b+2#0000000#ff404010| +0&#ffd7ff255@20
+| +0#0000e05#a8a8a8255@1|d+2#0000000#ff404010| +0&#ffd7ff255@21||+1&#ffffff0| +0#0000e05#a8a8a8255@1|z+2#0000000#ff404010| +0&#ffd7ff255@20||+1&#ffffff0| +0#0000e05#a8a8a8255@1|3+2#0000000#ff404010| +0&#ffd7ff255@20
+| +0#0000e05#a8a8a8255@1|-+0#4040ff13#afffff255@22||+1#0000000#ffffff0| +0#0000e05#a8a8a8255@1|u+2#0000000#ff404010| +0&#ffd7ff255@20||+1&#ffffff0| +0#0000e05#a8a8a8255@1|4+2#0000000#ff404010| +0&#ffd7ff255@20
+| +0#0000e05#a8a8a8255@1|-+0#4040ff13#afffff255@22||+1#0000000#ffffff0| +0#0000e05#a8a8a8255@1|-+0#4040ff13#afffff255@21||+1#0000000#ffffff0| +0#0000e05#a8a8a8255@1|d+0#0000000#5fd7ff255| @20
+| +0#0000e05#a8a8a8255@1|b+0#0000000#ffffff0|a|r| @19||+1&&| +0#0000e05#a8a8a8255@1|b+0#0000000#ffffff0|a|r| @18||+1&&| +0#0000e05#a8a8a8255@1|b+0#0000000#ffffff0|a|r| @18
+|~+0#4040ff13&| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|~| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|~| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|~| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|~| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|~| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|~| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|~| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|~| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|~| @23||+1#0000000&|~+0#4040ff13&| @22||+1#0000000&|~+0#4040ff13&| @22
+|X+3#0000000&|d|i|f|i|l|e|1| @4|1|,|1| @5|A|l@1| |X+1&&|d|i|f|i|l|e|2| @3|1|,|1| @5|A|l@1| |X|d|i|f|i|l|e|3| @3|1|,|1| @5|A|l@1
+|:+0&&> @73
diff --git a/src/testdir/test_diffmode.vim b/src/testdir/test_diffmode.vim
index 36d3d9b..b62266b 100644
--- a/src/testdir/test_diffmode.vim
+++ b/src/testdir/test_diffmode.vim
Binary files differ