Still having problems with this issue. I don't know if it is a recent history issue or files saved issue. Have played with about:config but not sure what I need to change to stop recent and downloaded files from my comp system (ubuntu 18.04) showing up in "open files" in firefox. Can anybody help?

To prevent recent and downloaded files from your computer system from showing up in the "Open Files" section in Firefox, you can adjust your Firefox settings. Here's how:

1)Open Firefox and type "about:preferences" in the address bar. 2)Scroll down to the "Files and Applications" section. 3)In the "Downloads" subsection, uncheck the box next to "Always ask you where to save files" if it is checked. 4)Next, click on the "Choose..." button next to "Save files to" and select a folder where you want your downloads to be saved. 5)In the "Applications" subsection, click on the "Applications" button. 6)Search for the file types that you do not want to show up in the "Open Files" section and change the action to "Save File" or "Always ask" instead of "Preview in Firefox."

By doing these steps, you are telling Firefox to save the downloaded files to a specific folder on your computer instead of showing them in the "Open Files" section. You are also telling Firefox not to preview certain file types in the browser, which can help prevent them from showing up in the "Open Files" section.