Sorry if i am not using QWt terminology becuase i am new to qwt and even qt it self.
I only used the RectItem of the navigation example, because you recommanded me to start with that. and i don't know what tools/ objects i need to use in qwt to do what i want to do.
but i think things now a lil clear to me than before.

For me it looks like you want to embed a second canvas ( what you call a rect ) inside of a plot canvas
Yes i think this will be the right object to represent my rect.
but can I draw the the embedded canves using four points according the the polt coordiante system ??

By ticks you probably mean that the embedded canvas has its own coordinate system and you want to have scales/axes showing it
Yes, but how can i do that ??

It also looks like you want to display plot items according to the coordinate system of the embedded canvas - at least a grid, but I guess there is more.

Yes, i wan to display a gird according to the embedded canves coordiante system. but other poltItems will be displayed accoding to the polt coordiante system, which mostly will be on the area of the embedded canvas (rect).

Thank you for your patience and help