Mixer: Define minimum height for mixer strips.

Mixer/Mixer.C

@@ -252,6 +252,9 @@ Mixer::rows ( int n )
     else
         sh = (scroll->h() - 18) / n;
 
+    if ( sh < Mixer_Strip::min_h() )
+        return;
+
     int tw = 0;
 
     for ( int i = 0; i < mixer_strips->children(); ++i )

Mixer/Mixer_Strip.H

@@ -52,6 +52,8 @@ class Mixer_Strip : public Fl_Group, public Loggable {
 
 public:
 
+    static int min_h ( void ) { return 250; }
+
     Mixer_Strip(int X, int Y, int W, int H, const char *L = 0);
     Mixer_Strip( const char *name, int channels );
     Mixer_Strip();                                              /* for log create */