User Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:50.0) Gecko/20100101 Firefox/50.0 Build ID: 20161209095719 Steps to reproduce: On Linux, with FF 49 or 50 (atleast). Disabling all extensions seems to help on some, but not on all cases. - Go to http://petrit.net/dragndrop.html - Select some text on some other application than Firefox. For example a texteditor. - Drag the text and drop it on the yellow area on the web page. - The page shows the content of event.dataTransfer.types in textarea. And the values of event.dataTransfer.getData(type) for types text/plain, text/html and text on other textareas. Actual results: The "types"-textarea shows only the types application/x-moz-file and Files as if some files were dragged. Other textareas are empty, i.e., drag-event does not contain text-data. Expected results: Types should include text/plain (and possibly text/html depending on where the text is dragged from), and the dragged text should be shown in the textarea for text/plain.
I don't see this on 53 when dragging from a textbox in another application or from gedit. Could you be more specific to to the application you are dragging from?
Gedit, Kate, Komodo, Chrome/Chromium or whatever application where you can drag text from. In Kubuntu I have the Firefox 50 from repositories and couple of extensions. For example: - ColorZilla - Ubuntu Modifications - Web Developer If any of those is enabled, the drag'n'drop fails. If they are all disabled, the "text/plain" can be obtaind successfully from drop-event. I tested also with Firefox that I downloaded directly from mozilla.org. Same with that. The third environment I tested this was the live-dvd-image of Fedora from getfedora.org. That has FF 49 and no extensions. In that environment drag from Gedit failed. Couple months ago d'n'd worked just fine. I managed to test this also with FF 46 and there was no problem.
That sounds like an issue with a extension then and not with Firefox itself. Are you testing with a clean profile each time?
I have tested both with clean profile and "non-clean". No matter. It isn't about any specific extension since if any of those is enabled, the d'n'd stops working. If I delete files extension.ini and extensions.json from the profile directory and then launch FF, d'n'd works fine, but if I close FF and restart it, then d'n'd fails again. (Those files are recreated.) I agree, that this most likely has something to do with extensions, but how. And on my tests only those extensions that require restart of FF, when enabled/disabled, affect the behaviour. For example Adblock Plus does not seem to make any difference. On the other hand, on that live-Fedora there were no extensions installed and it still failed. There the FF version was 49.