Very helpful add-on, but does not always work and has minimal documentation. ..
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Provides ability: ..
* to export individual bookmark folders to HTML ..
* to use mouse drag and drop to move bookmarks and folders ..
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Bugs and deficiencies: ..
* The tabzen manager window sometimes fails to show subfolder contents; contents do appear, however, on the tabzen menu
* Opening a folder of bookmarked files fails -- stops with no warning -- when loading a "file:///" user web-page ..
* Tabzen bookmarks do not include the dd-tag meta-data saved in bookmarks created by Firefox ..
* Arrow keys do not work in the manager window ..
* No way to copy entries in one folder and paste the copies in another ..