Don't allow 'Classic Filters' to be applied to mixed sample-rate tracks, as we don't support that.

Fix a typo in the name of 'Classic Filters'.
Improve consistency layout as we switch filter types.
Remove a win warning in EQ.
Improve some code readability / change styles (please don't shoot me for that!).   OK, possibly increased the inconsistency.

src/effects/Equalization.cpp

@@ -255,7 +255,7 @@ EffectEqualization::~EffectEqualization()
 bool EffectEqualization::Init()
 {
    int selcount = 0;
-   double rate;
+   double rate = 0.0;
    TrackListIterator iter(GetActiveProject()->GetTracks());
    Track *t = iter.First();
    while (t) {

src/effects/ScienFilter.cpp

@@ -126,8 +126,27 @@ EffectScienFilter::~EffectScienFilter()
 
 bool EffectScienFilter::Init()
 {
-   return(true);
+   int selcount = 0;
+   double rate = 0.0;
+   TrackListIterator iter(GetActiveProject()->GetTracks());
+   Track *t = iter.First();
+   while (t) {
+      if (t->GetSelected() && t->GetKind() == Track::Wave) {
+         WaveTrack *track = (WaveTrack *)t;
+         if (selcount==0) {
+            rate = track->GetRate();
          }
+         else {
+            if (track->GetRate() != rate) {
+               wxMessageBox(_("To apply a filter, all selected tracks must have the same sample rate."));
+               return(false);
+            }
+         }
+         selcount++;
+      }
+      t = iter.Next();
+   }
+   return(true);}
 
 bool EffectScienFilter::PromptUser()
 {
@@ -613,9 +632,7 @@ void ScienFilterDialog::MakeScienFilterDialog()
    // -------------------------------------------------------------------
    // ROW 2 and 3: Type, Order, Ripple, Subtype, Cutoff
    // -------------------------------------------------------------------
-   szr3 = new wxFlexGridSizer (6, 0, 0);
-   szr3->SetHGap(2);
-   szr3->SetVGap(5);
+   szr3 = new wxFlexGridSizer (6, 5, 2);  // 6 columns, 5px Vertical gap, 2px Horizontal gap
    flagslabel.Border(wxLEFT, 12).Align(wxALIGN_RIGHT | wxALIGN_CENTRE_VERTICAL );
    flagsunits.Align( wxALIGN_LEFT | wxALIGN_CENTRE_VERTICAL );
 
@@ -701,6 +718,11 @@ void ScienFilterDialog::MakeScienFilterDialog()
    szrStop->Add(st, flagsunits);
    szr3->Add(szrStop);
 
+   // Calculate the min size with both pass and stop-band attenuations showing, to stop them jumping around
+   szrPass->Show(true);
+   szrStop->Show(true);
+   szr3->SetMinSize(szr3->CalcMin());
+
    // -------------------------------------------------------------------
    // ROW 4: Subtype, Cutoff
    // -------------------------------------------------------------------

src/effects/ScienFilter.h

@@ -48,7 +48,7 @@ public:
    virtual ~EffectScienFilter();
 
    virtual wxString GetEffectName() {
-      return wxString(_("Classic Filter..."));
+      return wxString(_("Classic Filters..."));
    }
 
    virtual std::set<wxString> GetEffectCategories() {