What about this mess? Ideas to better rewrite it?
<p>This mess is working well, but if somebody has any ideas to make it look/perform better, it would be greatly appreciated!</p>

<pre><code>def OnButtonClick(b, e, f="none"):
    if b == Gui["goleft"]   and e == viz.UP: do_Cam([1.475, 7.862, 10.293])
    if b == Gui["gocenter"] and e == viz.UP: do_Cam([0, 1, 52])
    if b == Gui["goright"]  and e == viz.UP: do_Cam([0, 11, 5])
    if b == Gui["godown"]   and e == viz.UP: do_Cam([0, 16, 53])

def OnSliders(POS, S):
    if S == 1:
        Gui["bars_alpha"].message(str('%.2f'%(POS)))
        CFG["BAR_alpha"] = POS
        for i in BAR_Items: BAR_Items[i].alpha(POS)
    elif S == 2:
        Gui["shps_alpha"].message(str('%.2f'%(POS)))
        CFG["SHP_alpha"] = POS
        for i in ISOS.keys(): SHAPE[i+"_SHP"].alpha(POS)
    elif S == 3:
        Gui["bars_sizes"].message(str('%.2f'%(POS)))
        CFG["BAR_scale"] = [POS, 0.15, POS]
        for i in BAR_Items: BAR_Items[i].scale(POS, BAR_Items[i].getScale()[1], POS)
    elif S == 4:
        Gui["label_alpha"].message(str('%.2f'%(POS)))
        CFG["BARTXT_alpha"] = POS
        for i in BAR_Label: BAR_Label[i].alpha(POS)
    elif S == 5:
        Gui["label_size"].message(str('%.2f'%(POS)))
        CFG["BARTXT_scale"] = [POS, POS, POS]
        for i in BAR_Label: BAR_Label[i].scale(POS, POS, POS)
    elif S == 6:
        Gui["grid_alpha"].message(str('%.2f'%(POS)))
        CFG["grid_alpha"] = POS
        [Griditema[i].alpha(POS) for i in Griditema]
        [Griditemb[i].alpha(POS) for i in Griditemb]
</code></pre>

<p>After following some of the initial recommendations I received, I now have:</p>

<pre><code>def OnButtonClick(b, e, f="none"):
    if e != viz.UP: return
    if b == Gui["goleft"]   : do_Cam([1.475, 7.862, 10.293])
    elif b == Gui["gocenter"] : do_Cam([0, 1, 5])
    elif b == Gui["goright"]  : do_Cam([0, 1, 5])
    elif b == Gui["godown"]   : do_Cam([0, 1, 5])

def OnSliders(POS, S):
    if S == 1:
        CFG["BAR_alpha"] = POS
        for i in BAR_Items: BAR_Items[i].alpha(POS)
    elif S == 2:
        CFG["SHP_alpha"] = POS
        for i in ISOS.keys(): SHAPE[i+"_SHP"].alpha(POS)
    elif S == 3:
        CFG["BAR_scale"] = [POS, 0.15, POS]
        for i in BAR_Items: BAR_Items[i].scale(POS, BAR_Items[i].getScale()[1], POS)
    elif S == 4:
        CFG["BARTXT_alpha"] = POS
        for i in BAR_Label: BAR_Label[i].alpha(POS)
    elif S == 5:
        CFG["BARTXT_scale"] = [POS, POS, POS]
        for i in BAR_Label: BAR_Label[i].scale(POS, POS, POS)
    elif S == 6:
        CFG["grid_alpha"] = POS
        for i in Griditema: Griditema[i].alpha(POS)
        for i in Griditemb: Griditemb[i].alpha(POS)

    mydict  = {1:"bars_alpha", 2:"shps_alpha", 3:"bars_sizes", 4:"label_alpha", 5:"label_size", 6:"grid_alpha"}
    Gui[mydict[S]].message('%.2f' % POS)
</code></pre>

<p>This is how it ended:</p>

<pre><code>def OnButtonClick(b, e, f="none"):
    if e != viz.UP: return
    if b == Gui["goleft"]    : do_Cam([1.475, 7.862, 10.293])
    elif b == Gui["gocenter"]: do_Cam([0, 1, 5])
    elif b == Gui["goright"] : do_Cam([0, 1, 5])
    elif b == Gui["godown"]  : do_Cam([0, 1, 5])

def OnSliders(POS, S):
    D = {1:"BAR_alpha", 2:"SHP_alpha", 3:"BAR_scale", 4:"TXT_alpha", 5:"TXT_scale", 6:"grid_alpha"}
    if   S == 1: CFG[D[S]] = POS; [BAR_Items[i].alpha(POS) for i in BAR_Items]
    elif S == 2: CFG[D[S]] = POS; [SHAPE[i+"_SHP"].alpha(POS) for i in ISOS.keys()] 
    elif S == 3: CFG[D[S]] = [POS, 0.15, POS]; [BAR_Items[i].scale(POS, BAR_Items[i].getScale()[1], POS) for i in BAR_Items]
    elif S == 4: CFG[D[S]] = POS; [BAR_Label[i].alpha(POS) for i in BAR_Label]
    elif S == 5: CFG[D[S]] = [POS, POS, POS]; [BAR_Label[i].scale(POS, POS, POS) for i in BAR_Label]
    elif S == 6: CFG[D[S]] = POS; [Griditema[i].alpha(POS) for i in Griditema]; [Griditemb[i].alpha(POS) for i in Griditemb]
    Gui[D[S]].message('%.2f' % POS)
</code></pre>

<p>Thanks for the help!</p>
