"The last "advanced: creating objects. In Dia's lingo,
"object" means "a predefined bunch of lines that means something
specific". So in your toolbox, look at the spot that says "Misc".
Now look below it: you'll see a clock, a folder, etc. Make a clock
just like you would with anything else: click and drag. Try a
folder too.
"You might be wondering why Dia offers an "folder" object to
draw... which brings up the entire point of objects. They're meant
to be extensions of Dia for different (more specialized) tasks.
"Misc" could be useful for making a diagram of a filesystem. Click
"Misc", then "Other sheets', and you'll see a menu of a lot of
possible objects. Try "Flowchart." Suddenly, you have a lot of
handy flowchart objects."