Document Tabs Options

Color tabs based on validation errors and warnings - Check this box to color document tabs based on whether the document has errors and warnings after it has been validated. If the document has one or more errors, than a red hue is used to color the document's tab. If the document has no errors but it has one or more warnings, then a yellow hue is used. If the document has no errors and no warnings then a green hue is used. This option is enabled by default. (New v14.0)

Use multi-line tabs - Check this box to use multi-line document tabs. The tabs will also be stretched to fit the line. Unchecking this box will cause the tabs to be in a single, scrollable line like in v12 and prior versions. This option is enabled by default. (New v14.0011)
 
Note that in v17.0211+, this option may be automatically disabled if there are "too many" open documents in order to reduce the space consumed by the tabs (see the 'Max documents open before switching to single-line tabs' option). In this case you may want to use the Open Documents window (View->Windows->Open Documents) to switch documents.

Max documents open before switching to single-line tabs - If the number of open documents exceeds this number then the editor will switch to a single line of document tabs regardless of the 'Use multi-line tabs' setting. This purpose of this feature is to reduce the amount of editor space taken up by the document tabs when there are many open documents. The minimum is 5 and there is no set maximum although it is recommended that this option not be set too high or various problems may result from too many rows of document tabs. The default value is 100. (New v17.0303)