Another clipping fix: default back to using window size to calculate clipping on viewports which don't have a rendertarget which fixes clipping on the editor viewport.

drivers/gles2/rasterizer_gles2.cpp

@@ -9348,10 +9348,23 @@ void RasterizerGLES2::canvas_render_items(CanvasItem *p_item_list,int p_z,const
 				int w = current_clip->final_clip_rect.size.x;
 				int h = current_clip->final_clip_rect.size.y;
 */
-				int x = current_clip->final_clip_rect.pos.x;
-				int y = viewport.height-(current_clip->final_clip_rect.pos.y+current_clip->final_clip_rect.size.y);
-				int w = current_clip->final_clip_rect.size.x;
-				int h = current_clip->final_clip_rect.size.y;
+				int x;
+				int y;
+				int w;
+				int h;
+
+				if (current_rt) {
+					x = current_clip->final_clip_rect.pos.x;
+					y = viewport.height - (current_clip->final_clip_rect.pos.y + current_clip->final_clip_rect.size.y);
+					w = current_clip->final_clip_rect.size.x;
+					h = current_clip->final_clip_rect.size.y;
+				}
+				else {
+					x = current_clip->final_clip_rect.pos.x;
+					y = window_size.height - (current_clip->final_clip_rect.pos.y + current_clip->final_clip_rect.size.y);
+					w = current_clip->final_clip_rect.size.x;
+					h = current_clip->final_clip_rect.size.y;
+				}
 
 				glScissor(x,y,w,h);