diff --git a/src/visualization.jl b/src/visualization.jl
index ec4e778..7d1a066 100644
--- a/src/visualization.jl
+++ b/src/visualization.jl
@@ -76,6 +76,8 @@ function build_ui(U, V, Du, Dv, F, k, params_obs, heat_obs)
 
     run_label = Observable{String}("Run")
     stepsize = Observable(30)
+    spoint = select_point(ax.scene)
+
     # # Controls
     fig[2, 1] = buttongrid = GridLayout(ax.scene, tellwidth=false)
     btn_step = Button(buttongrid[1, 1], width=50, label="Step")
@@ -130,6 +132,27 @@ function build_ui(U, V, Du, Dv, F, k, params_obs, heat_obs)
         reset!(U, V, heat_obs)
 
     end
+    on(spoint) do pt
+        r = 5
+        if pt === nothing
+            return
+        end
+        x, y = pt
+        println("params_obs[].N, ", params_obs[].N)
+        i, j = coord_to_index(x, y, params_obs[].N)
+
+        # get corners of square that will get filled with concentration
+        imin = max(i - r, 1)
+        imax = min(i + r, params_obs[].N)
+        jmin = max(j - r, 1)
+        jmax = min(j + r, params_obs[].N)
+
+        # set disbalanced concentration of U and V
+        U[imin:imax, jmin:jmax] .= 0.5
+        V[imin:imax, jmin:jmax] .= 0.25
+
+        heat_obs[] = copy(U)
+    end
     return fig
 end