Change return type of border_size to u16

src/sdl2/video.rs

@@ -1161,13 +1161,13 @@ impl Window {
     }
     
     /// Use this function to get the size of a window's borders (decorations) around the client area.
-    pub fn border_size(&self) -> (i32, i32, i32, i32) {
+    pub fn border_size(&self) -> (u16, u16, u16, u16) {
         let mut top: c_int = 0;
         let mut left: c_int = 0;
         let mut bottom: c_int = 0;
         let mut right: c_int = 0;
         unsafe { sys::SDL_GetWindowBordersSize(self.context.raw, &mut top, &mut left, &mut bottom, &mut right) };
-        (top as i32, left as i32, bottom as i32, right as i32)
+        (top as u16, left as u16, bottom as u16, right as u16)
     }
 
     pub fn set_size(&mut self, width: u32, height: u32)