I am trying to make this tikzpicture using the answer from Drawing manifolds in tikz but I can not make the intersection of U and V gray. If I make U and V white then the intersection would be white too. My question is how can I make the intersection gray and keeping everything else white ?
\documentclass[border=5mm,tikz]{standalone}
\usepackage{amssymb}
\usepackage{pgfplots}
\usepgfplotslibrary{patchplots}
\usetikzlibrary{patterns, positioning, arrows}
\pgfplotsset{compat=1.15}
\begin{document}
\begin{figure}[h]
\centering
\begin{tikzpicture}
% Functions i
\path[->] (0.8, 0) edge [bend right] node[left, xshift=-2mm] {$\varphi$} (-1, -2.9);
\draw[white,fill=white] (0.06,-0.57) circle (.15cm);
% Functions j
\path[->] (4.2, 0) edge [bend left] node[right, xshift=2mm] {$\psi$} (6.2, -2.8);
\draw[white, fill=white] (4.54,-0.12) circle (.15cm);
% Manifold
\draw[smooth cycle] plot coordinates{(2,2) (-0.5,0) (3,-2) (5,1)} node at (3,2.3) {$M$};
% Help lines
%\draw[help lines] (-3,-6) grid (8,6);
% Subsets
\draw[smooth cycle, dashed]
plot coordinates {(1,0) (1.5, 1.2) (2.5,1.3) (2.6, 0.4)}
node [label={[label distance=-0.3cm, xshift=-2cm, fill=white]:$U$}] {};
\draw[smooth cycle, dashed]
plot coordinates {(4, 0) (3.7, 0.8) (3.0, 1.2) (2.5, 1.2) (2.2, 0.8) (2.3, 0.5) (2.6, 0.3) (3.5, 0.0)}
node [label={[label distance=-0.8cm, xshift=.75cm, yshift=1cm, fill=white]:$V$}] {};
% First Axis
\draw[thick, ->] (-3,-5) -- (0, -5) {};
\draw[thick, ->] (-3,-5) -- (-3, -2) {};
% Arrow from i to j
\path[->] (0, -3.85) edge [bend left] node[midway, above]{$\psi_{ij}$} (4.5, -3.85);
% Second Axis
\draw[thick, ->] (5, -5) -- (8, -5) node [label=above:$\phi_j(U_j)$] {};
\draw[thick, ->] (5, -5) -- (5, -2) node [label=right:$\mathbb{R}^m$] {};
% Sets in R^m
\draw[white] (-0.67, -3.06) -- +(180:0.8) arc (180:270:0.8);
\fill[even odd rule, white] [smooth cycle] plot coordinates{(-2, -4.5) (-2, -3.2) (-0.8, -3.2) (-0.8, -4.5)} (-0.67, -3.06) -- +(180:0.8) arc (180:270:0.8);
\draw[smooth cycle, dashed] plot coordinates{(-2, -4.5) (-2, -3.2) (-0.8, -3.2) (-0.8, -4.5)};
\draw [dashed] (-1.45, -3.06) arc (180:270:0.8);
\draw[white] (5.7, -3.06) -- +(-90:0.8) arc (-90:0:0.8);
\fill[even odd rule, white] [smooth cycle] plot coordinates{(7, -4.5) (7, -3.2) (5.8, -3.2) (5.8, -4.5)} (5.7, -3.06) -- +(-90:0.8) arc (-90:0:0.8);
\draw[smooth cycle] plot coordinates{(7, -4.5) (7, -3.2) (5.8, -3.2) (5.8, -4.5)};
\draw (5.69, -3.85) arc (-90:0:0.8);
\end{tikzpicture}
\end{figure}
\end{document}

