Destroy the old video context when detaching video

It was previously not being destroyed until video was reattached, which
wasted VRAM and caused problems on OS X.

Originally committed to SVN as r6927.

aegisub/src/dialog_detached_video.cpp

@@ -66,6 +66,8 @@ DialogDetachedVideo::DialogDetachedVideo(agi::Context *context)
 
 	SetTitle(wxString::Format(_("Video: %s"), wxFileName(context->videoController->GetVideoName()).GetFullName()));
 
+	old_display->Unload();
+
 	// Video area;
 	VideoBox *videoBox = new VideoBox(this, true, context);
 	context->videoDisplay->SetMinClientSize(old_display->GetClientSize());
@@ -103,17 +105,16 @@ DialogDetachedVideo::DialogDetachedVideo(agi::Context *context)
 DialogDetachedVideo::~DialogDetachedVideo() { }
 
 void DialogDetachedVideo::OnClose(wxCloseEvent &evt) {
-	// Deleting a GL context seems to invalidate ALL contexts, so we need to
-	// delete both the detached and undetached contexts here, then recreate
-	// the undetached one later
 	context->videoDisplay->Destroy();
-	old_display->Reload();
 
 	context->videoDisplay = old_display;
 	context->videoSlider = old_slider;
 
 	OPT_SET("Video/Detached/Enabled")->SetBool(false);
 
+	if (context->videoController->IsLoaded())
+		context->videoController->JumpToFrame(context->videoController->GetFrameN());
+
 	evt.Skip();
 }
 

aegisub/src/video_display.cpp

@@ -420,11 +420,8 @@ Vector2D VideoDisplay::GetMousePosition() const {
 	return mouse_pos ? tool->ToScriptCoords(mouse_pos) : mouse_pos;
 }
 
-void VideoDisplay::Reload() {
+void VideoDisplay::Unload() {
 	glContext.reset();
 	videoOut.reset();
 	tool.reset();
-
-	if (con->videoController->IsLoaded())
-		con->videoController->JumpToFrame(con->videoController->GetFrameN());
 }

aegisub/src/video_display.h

@@ -171,5 +171,5 @@ public:
 	bool ToolIsType(std::type_info const& type) const;
 
 	/// Discard all OpenGL state
-	void Reload();
+	void Unload();
 };