Index: modules/swing/src/main/java/common/javax/swing/text/GapContent.java =================================================================== --- modules/swing/src/main/java/common/javax/swing/text/GapContent.java (revision 483865) +++ modules/swing/src/main/java/common/javax/swing/text/GapContent.java (working copy) @@ -143,7 +143,7 @@ throw new BadLocationException("Length must be non-negative", length); } - if (offset < 0 || offset + length > length()) { + if (offset < 0 || length > length() - offset) { throw new BadLocationException("Invalid start position", offset); }