The phrase "inside of the window" is correct and usable in written English.
It can be used when describing something that is located within the physical boundaries of a window.
Example: "The cat was sitting inside of the window, enjoying the warm sunlight."
Alternatives: "inside the window" or "within the window."
It was winter and you've got condensation on the inside of the window.
Wood on the inside of the window frames complements the cedar-clad ceiling and fir beams spanning the living space.
The cleaners have to hold onto the inside of the window frame with one hand and, with half their bodies hanging out the window, clean the window from the outside.
By the time I got there the bees were motionless and starving on the inside of the window so I put a box of honeycomb underneath and they immediately latched on to it".
All of these materials work in basically the same manner: You fasten them in place against the stop molding around the inside of the door or window so the resilient face presses against the inside of the window sash or door when it is closed.
The Swiss architect built the diminutive dwelling in 1952 on a hillside in Roquebrune-Cap-Martin, France, where he summered until his death in 1965, and the design of its 160-square-foot interior was all about context — he affixed mirrors to the inside of the window shutters to maximize the stunning views of the coastline.
It was really a cold-water flat, there was ice on the inside of the windows!
Two Pasdaran soldiers were guarding the front door, and either cardboard or blankets covered the inside of the windows.
Let's wind him up by cleaning the condensation off the inside of the windows using our bare hands".
Occasionally, the driver would draw a curtain around the inside of the windows, and attach a flashing blue light to the roof before setting off.
But the house was barricaded at night, with shutters, locks and bars on the inside of the windows, making it impossible to open them from the outside.
