Use the native placeholder text functionality on OS X

aegisub/src/osx_utils.mm

@@ -24,6 +24,7 @@
 #include "config.h"
 
 #include <wx/window.h>
+#include <wx/osx/core/cfstring.h>
 
 #import <AppKit/AppKit.h>
 
@@ -54,3 +55,11 @@ void SetFloatOnParent(wxWindow *window) {
                      queue:nil
                 usingBlock:^(NSNotification *) { [nsWindow setLevel:NSFloatingWindowLevel]; }];
 }
+
+void SetPlaceholderText(wxWindow *window, wxString const& placeholder) {
+    id nsWindow = window->GetHandle();
+    if ([nsWindow respondsToSelector:@selector(cell)]) {
+        NSTextFieldCell *cell = [nsWindow cell];
+        cell.placeholderString = wxCFStringRef(placeholder).AsNSString();
+    }
+}

aegisub/src/placeholder_ctrl.h

@@ -42,6 +42,7 @@ class Placeholder : public BaseCtrl {
 		BaseCtrl::Create(parent, -1, placeholder, wxDefaultPosition, size, style);
 	}
 
+#ifndef __WXOSX__
 	/// Focus gained event handler
 	void OnSetFocus(wxFocusEvent& evt) {
 		evt.Skip();
@@ -104,6 +105,16 @@ public:
 			return "";
 		return BaseCtrl::GetValue();
 	}
+#else
+public:
+	Placeholder(wxWindow *parent, wxString const& placeholder, wxSize const& size, long style, wxString const& tooltip)
+	: placeholder(placeholder)
+	{
+		Create(parent, size, style);
+		BaseCtrl::SetToolTip(tooltip);
+		SetPlaceholderText(this, placeholder);
+	}
+#endif
 };
 
 template<> inline void Placeholder<wxComboBox>::Create(wxWindow *parent, wxSize const& size, long style) {

aegisub/src/subs_edit_box.cpp

@@ -316,10 +316,6 @@ void SubsEditBox::PopulateActorList() {
 		if (AssDialogue *diag = dynamic_cast<AssDialogue*>(*it))
 			actors.insert(diag->Actor);
 	}
-#ifdef __APPLE__
-	// OSX doesn't like combo boxes that are empty.
-	actors.insert("Actor");
-#endif
 	actors.erase("");
 	wxArrayString arrstr;
 	arrstr.reserve(actors.size());

aegisub/src/utils.h

@@ -99,6 +99,8 @@ void AddFullScreenButton(wxWindow *window);
 
 void SetFloatOnParent(wxWindow *window);
 
+void SetPlaceholderText(wxWindow *window, wxString const& placeholder);
+
 /// Forward a mouse wheel event to the window under the mouse if needed
 /// @param source The initial target of the wheel event
 /// @param evt The event