Currently, when user deletes filename template in Spectacle settings, we use this empty template and results can look weird. For example, if base directory for screenshots is ~/Pictures, Spectacle will create screenshots with names like ~/Pictures.png ~/Pictures-1.png, ~Pictures-2.png etc.
With this patch, Spectacle will create single-number names with empty template: ~/Pictures/1.png, ~/Pictures/2.png etc.
KSnaphot could behave similarly when given single-number name.
Reported by Vladimir Ivanov.
FIXED-IN: KDE Applications 18.04