Today I updated my FireFox browser and Joomla 1.5x administrator panel stopped working in it. Looks like Joomla 1.5x administrator panel contains some staff that prevents it from working in all modern browsers except Internet Explorer, or at least Internet Explorer is the only browser that displays message “Only secure content is displayed.” and button “Show All Content” enabling some insecure mode. To eliminate the need of pressing this button each time I open new page in administrator panel I went to “Internet Options->Security Tab->Miscellaneous->Display mixed content” and chose “Enable”:
