Constant Wet Area Below Window.. Roof or Window Leak?

I don't know the layout of your trailer, where the window is located, etc. but I had a leak under the front/side window of my '93 Wilderness that I could find no fault around the window. I found the screws on the hinge of the cover of the front window were loose. Somehow the water worked around the front corner and on to the shelf under the side window. I tightened the screws, caulked the top of the hinge and no more leak. No sign of a leak on the wall. Just a thought.. Good luck...