Fixed last of -Wcast-qual warnings

For vtkKCoreLayout, just alloc & copy the string.

For vtkInteractorStyleUser, init to nullptr instead of empty string.
It’s taking the char* owned by the vtkRenderWindowInteractor, which looks like it can be null anyway.
Adjusted usage to be prepared for null.

Also fixed some related indentation and comments.

Common/Core/vtkSetGet.h

@@ -118,10 +118,10 @@ virtual void Set##name (const char* _arg) \
     this->name = cp1; \
     do { *cp1++ = *cp2++; } while ( --n ); \
   } \
-   else \
-   { \
+  else \
+  { \
     this->name = nullptr; \
-   } \
+  } \
   this->Modified(); \
 }
 

Infovis/Layout/vtkKCoreLayout.cxx

@@ -176,12 +176,10 @@ int vtkKCoreLayout::RequestData(vtkInformation* vtkNotUsed(request),
   // graph size
   vtkIdType num_verts = output->GetNumberOfVertices();
 
-  if(this->KCoreLabelArrayName)
-  {
-  }
-  else
+  if(!this->KCoreLabelArrayName)
   {
-    this->KCoreLabelArrayName = (char*)"kcore";
+    const char * kcore = "kcore";
+    this->KCoreLabelArrayName = strcpy(new char [strlen(kcore)+1], kcore);
   }
 
   // Get the kcore attribute array

Interaction/Style/vtkInteractorStyleUser.cxx

@@ -33,7 +33,7 @@ vtkInteractorStyleUser::vtkInteractorStyleUser()
   this->ShiftKey = 0;
   this->CtrlKey = 0;
   this->Char = '\0';
-  this->KeySym = (char *)("");
+  this->KeySym = nullptr;
   this->Button = 0;
 }
 
@@ -54,7 +54,7 @@ void vtkInteractorStyleUser::PrintSelf(ostream& os, vtkIndent indent)
   os << indent << "ShiftKey: " << this->ShiftKey << "\n";
   os << indent << "CtrlKey: " << this->CtrlKey << "\n";
   os << indent << "Char: " << this->Char << "\n";
-  os << indent << "KeySym: " << this->KeySym << "\n";
+  os << indent << "KeySym: " << (this->KeySym ? this->KeySym : "(null)") << "\n";
   os << indent << "Button: " << this->Button << "\n";
 }
 

Interaction/Style/vtkInteractorStyleUser.h

@@ -68,7 +68,7 @@ public:
   //@{
   /**
    * Test whether modifiers were held down when mouse button or key
-   * was pressed
+   * was pressed.
    */
   vtkGetMacro(ShiftKey,int);
   vtkGetMacro(CtrlKey,int);
@@ -83,8 +83,8 @@ public:
 
   //@{
   /**
-   * Get the KeySym (in the same format as Tk KeySyms) for a
-   * KeyPress or KeyRelease method.
+   * Get the KeySym (in the same format as vtkRenderWindowInteractor KeySyms)
+   * for a KeyPress or KeyRelease method.
    */
   vtkGetStringMacro(KeySym);
   //@}

Rendering/Core/vtkRenderWindowInteractor.h

@@ -525,7 +525,7 @@ public:
   /**
    * Set/get the key symbol for the key that was pressed. This is the key
    * symbol as defined by the relevant X headers. On X based platforms this
-   * corresponds to the installed X sevrer, whereas on other platforms the
+   * corresponds to the installed X server, whereas on other platforms the
    * native key codes are translated into a string representation.
    */
   vtkSetStringMacro(KeySym);