Gave colour to buttons

interface/CBD/main.py

@@ -316,20 +316,20 @@ def make_probe():
     core.set_mode("ProbeBlock")
 
 buttons = [
-        Button(root, text="+", command=addition), 
-        Button(root, text="-x", command=negation), 
-        Button(root, text="*", command=multiply), 
-        Button(root, text="1/x", command=inverse), 
-        Button(root, text="Constant", command=constant), 
-        Button(root, text="Delay", command=delay), 
-        Button(root, text="d/dx", command=derivator), 
-        Button(root, text="integrator", command=integrator), 
-        Button(root, text="Probe", command=make_probe),
-        Button(root, text="Link", command=link), 
-        Button(root, text="InitialCondition", command=ic), 
-        Button(root, text="SIM", command=simulate), 
-        Button(root, text="STEP", command=step), 
-        Button(root, text="PAUSE", command=pause), 
+        Button(root, text="+", command=addition, bg="red"),
+        Button(root, text="-x", command=negation, bg="red"),
+        Button(root, text="*", command=multiply, bg="red"),
+        Button(root, text="1/x", command=inverse, bg="red"),
+        Button(root, text="Constant", command=constant, bg="red"),
+        Button(root, text="Delay", command=delay, bg="red"),
+        Button(root, text="d/dx", command=derivator, bg="red"),
+        Button(root, text="integrator", command=integrator, bg="red"),
+        Button(root, text="Probe", command=make_probe, bg="red"),
+        Button(root, text="Link", command=link, bg="blue"),
+        Button(root, text="InitialCondition", command=ic, bg="blue"),
+        Button(root, text="SIM", command=simulate, bg="green"),
+        Button(root, text="STEP", command=step, bg="green"),
+        Button(root, text="PAUSE", command=pause, bg="green"),
     ]
 
 for i, b in enumerate(buttons):