Suppose the default name is "x.zip". I noticed DownloadStudio tries to force the resultant file to have the same extension as the default. However, there are times in which that isn't desirable. The default extension might be wrong. LOG files are just TXT files with a different extension. As is, when I give the file name editor the focus and type a letter, DownloadStudio would add the character I just typed followed by ".zip". Which would be what you intended--if the caret ended up just before the period instead of the start of the string.

It gets worse. If there is no period in the default name, DownloadStudio keeps adding the default name to what you typed.