Rhelper=function(topic)
{
	library(RGtk2);
	
	## Window and containers
	window.main=gtkWindow("toplevel",show=FALSE);
	window.main$setTitle("Rhelper");
	window.main$setDefaultSize(800,600);
	hbox.main=gtkHBoxNew(homogeneous=FALSE);
	sw1.main=gtkScrolledWindowNew(show=TRUE);
	sw2.main=gtkScrolledWindowNew(show=TRUE);
	sw1.main$setPolicy(GtkPolicyType["automatic"],GtkPolicyType["automatic"]);
	sw2.main$setPolicy(GtkPolicyType["automatic"],GtkPolicyType["automatic"]);
	sw1.main$setSizeRequest(200,-1);
	## Listbox
	model.main=gtkListStoreNew("gchararray");
	listbox.main=gtkTreeViewNewWithModel(model.main);
	renderer.main=gtkCellRendererTextNew();
	column.main=gtkTreeViewColumnNewWithAttributes("",renderer.main,text=0);
	listbox.main$appendColumn(column.main);
	selection.main=gtkTreeViewGetSelection(listbox.main);
	selection.main$setMode(GtkSelectionMode["single"]);
	setListbox=function(topic,model,column,selection)
	{
		helpfile=as.character(help(topic))[1];
		pkgname=basename(dirname(dirname(helpfile)));
		indexfile=file.path(dirname(helpfile),"AnIndex");
		fun.name=readLines(indexfile)[-1];
		fun.name=gsub("\t.*","",fun.name);
		if(pkgname!=gsub("Package: ","",column$getTitle()))
		{
			model$clear();
			for(fname in fun.name)
			{
				model$set(model$append()$iter,0,fname);
			}
			column$setTitle(paste("Package:",pkgname));
		}
		index=which(fun.name==topic)[1]-1;
#	iter=.RGtkCall("S_gtk_list_store_insert_with_valuesv",model, 
#			as.integer(index),as.integer(0),list(topic))$iter;
#	model$remove(iter);
#	selection$selectIter(iter);
		iter=model$insert(index)$iter;
		model$remove(iter);
		selection$selectIter(iter);
	}
	## TextView
	buffer.main=gtkTextBufferNew();
	textview.main=gtkTextView(buffer=buffer.main,show=TRUE);
	textview.main$setEditable(FALSE);
	textview.main$setWrapMode(GtkWrapMode["word"]);
	textview.main$setLeftMargin(10);
	textview.main$setRightMargin(10);
	## Tags
	tag.title=buffer.main$createTag("title",foreground="#666666",
			family="monospace",scale=PANGO_SCALE_XX_LARGE,
			weight=PangoWeight["bold"],justification="center",
			pixels_above_lines=20,pixels_below_lines=20);
	tag.section=buffer.main$createTag("section",foreground="#666666",
			family="monospace",scale=PANGO_SCALE_X_LARGE,
			weight=PangoWeight["bold"],pixels_above_lines=15,
			pixels_below_lines=12);
	tag.text=buffer.main$createTag("text",scale=PANGO_SCALE_LARGE,
			family="sans",pixels_above_lines=8,pixels_below_lines=8);
	tag.code=buffer.main$createTag("code",foreground="#888888",
			scale=PANGO_SCALE_LARGE,weight=PangoWeight["bold"],
			family="monospace",pixels_above_lines=8,
			pixels_below_lines=8);
	tag.RCODE=buffer.main$createTag("RCODE",scale=PANGO_SCALE_LARGE,
			family="monospace");
	tag.emph=buffer.main$createTag("emph",style="italic",
			scale=PANGO_SCALE_LARGE,left_margin=50,
			pixels_above_lines=8,pixels_below_lines=8);
	tag.bold=buffer.main$createTag("bold",family="sans",scale=PANGO_SCALE_LARGE,
			weight=PangoWeight["bold"],pixels_above_lines=8,
			pixels_below_lines=8);
	tag.arg=buffer.main$createTag("arg",foreground="#888888",
			scale=PANGO_SCALE_LARGE,weight=PangoWeight["bold"],
			family="monospace");
	tag.discrip=buffer.main$createTag("discrip",scale=PANGO_SCALE_LARGE,
			family="sans",left_margin=50,pixels_above_lines=8,
			pixels_below_lines=8);
	## Rd parser
	sections0=c("description","usage","arguments","details","value",
			"references","note","author","seealso","examples","section",
			"source","format");
	sections0.name=c("Description","Usage","Arguments","Details","Value",
			"References","Note","Author(s)","See Also","Examples","...",
			"Source","Format");
	getTags=function(section)
	{
		f=function(x)
		{
			s=if(length(x)==0) "" else if(is.list(x)) list(getTags(x)) else x;
			names(s)=attr(x,"Rd_tag");
			return(s);
		}
		tags=unlist(lapply(section,f));
		names(tags)=gsub("\\\\","",names(tags));
		return(tags);
	}
	tidy=function(section,section.title)
	{
		section=getTags(section);
		section=gsub("^ +\n","\n",section);
		if(section.title=="...")
		{
			section.title=section[1];
			section=section[-1];
		}
		tags=names(section);
		index.dontrun=grep("dontrun",tags);
		section[index.dontrun[1]]=paste("## Not run:",
				section[index.dontrun[1]]);
		section[index.dontrun[length(index.dontrun)]]=
				paste(section[index.dontrun[length(index.dontrun)]],
						"## End(Not run)",sep="\n");
		tags[index.dontrun]="RCODE";
		index.pre=grep("preformatted",tags);
		tags[index.pre]="RCODE";
		index.RCODE=grep("^RCODE$",tags);
		tmp=section[index.RCODE];
		tags=gsub("itemize","enumerate",tags);
		section[grep("enumerate.item",tags)-1]="\n";
		
		index1=grep("^\n$",section);
		index1=index1[index1<length(section)];
		section[index1+1]=gsub("^ +","",section[index1+1]);
		
		index2=grep(".+\n$",section);
		index2=index2[index2<length(section)];
		section[index2]=gsub("\n$","",section[index2]);
		section[index2+1]=gsub("^ +"," ",section[index2+1]);
		index.exception=c(1,index2+1,grep("item|enumerate|^RCODE$",tags)+1)
		section[setdiff(index1,index.exception)]=" ";
		section[grep("enumerate",tags)[1]]="";
		
		section[grepl("dot",tags)]="...";
		tags=gsub(".*dot.*","RCODE",tags);
		section[grepl("R$",tags)]="R";
		tags=gsub("R$","code",tags);
		section[grepl("enumerate.item",tags)]="*";
		section[grepl("dontshow",tags)]="";
		section[grepl("sQuote",tags)]=paste("\'",section[grepl("sQuote",tags)],"\'",sep="");
		section[grepl("dQuote",tags)]=paste("\"",section[grepl("dQuote",tags)],"\"",sep="");
		
		if(section.title=="Arguments")
		{
			index3=grep("^$",section);
			tags[index3+1]="arg";
			section[index3+1]=paste(section[index3+1],"\n",sep="");
		}
		tags=gsub(".*emph.*","emph",tags);
		tags=gsub(".*bold.*|.*strong.*|.*pkg.*","bold",tags);
		tags=gsub(".*file.*","code",tags);
		tags=gsub(".*link.*|.*url.*","link",tags);
		tags=gsub(".*code.*","code",tags);
		tags=gsub(".*item.*|.*enumerate.*","discrip",tags);
		
		section[index.RCODE]=tmp;
		names(section)=tags;
		section=c(section.title,section);
		section=section[section!=""];
		flag=TRUE;
		while(flag)
		{
			index.returnEnd=grep("\n$",section);
			index.returnBegin=grep("^\n",section);
			index.RCODE=grep("^RCODE$",names(section));
			index.dup=setdiff(intersect(index.returnEnd+1,index.returnBegin),index.RCODE);
			flag=length(index.dup)>0;
			if(flag) section=section[-index.dup];
		}
		return(section);
	}
# Write text
	writeText=function(topic,buf)
	{
		helpfile=as.character(help(topic))[1];
		pkgname=basename(dirname(dirname(helpfile)));
		docname=basename(helpfile);
		RdDB=file.path(dirname(helpfile),pkgname);
		Rdobj=tools:::fetchRdDB(RdDB,docname);
		
		sections=tools:::RdTags(Rdobj);
		sections.indices=!grepl("title|name|alias|keyword|concept",sections);
		sections=sections[sections.indices];
		sections=gsub("\\\\","",sections);
		sections.title=sections0.name[match(sections,sections0)];
		contents=mapply(tidy,Rdobj[sections.indices],sections.title,SIMPLIFY=FALSE);
		
		buf$setText("");
		iter.t=buf$getIterAtOffset(0)$iter;
		buf$insertWithTagsByName(iter.t,
				tools:::.Rd_get_metadata(Rdobj,"title"),"title");
		buf$insert(iter.t,"\n");
		for(i in 1:length(contents))
		{
			buf$insertWithTagsByName(iter.t,contents[[i]][1],"section");
			for(j in 2:length(contents[[i]]))
			{
				if(names(contents[[i]][j]) %in% c("RCODE","arg","discrip",
						"code","emph","bold"))
				{
					buf$insertWithTagsByName(iter.t,contents[[i]][j],
							names(contents[[i]][j]));
				}else if(names(contents[[i]][j])=="link")
				{
					tag.link=buffer.main$createTag(NULL,foreground="blue",underline="single",
							scale=PANGO_SCALE_LARGE,weight=PangoWeight["bold"],
							family="monospace",pixels_above_lines=8,
							pixels_below_lines=8);
					tag.link$setData("link",contents[[i]][j]);
					buf$insertWithTags(iter.t,contents[[i]][j],tag.link);
				}else{
					buf$insertWithTagsByName(iter.t,contents[[i]][j],"text");
				}
			}
		}
	}
	## Signal
	change_text=function(selection,param)
	{
		if(!selection$getSelected()$retval) return(FALSE);
		iter=selection$getSelected()$iter;
		val=param$model$getValue(iter,0)$value;
		writeText(val,param$buffer);
	}
	link_clicked=function(object,event,param)
	{
		if(event$type!=GdkEventType['button-release']-1) return(FALSE);
		if(event$button!=1) return(FALSE);
		buffer=object$getBuffer();
		iter.bounds=buffer$getSelectionBounds();
		if(iter.bounds$start$getOffset()!=iter.bounds$end$getOffset()) return(FALSE);
		buffer.coords=object$windowToBufferCoords(GtkTextWindowType["widget"],event$x,event$y);
		iter=object$getIterAtLocation(buffer.coords$buffer.x,buffer.coords$buffer.y)$iter;
		if(length(iter$getTags())<1) return(FALSE);
		link=iter$getTags()[[1]]$getData("link");
		if(!is.null(link))
		{
			if(!grepl("http",link))
			{
				setListbox(gsub("\"|\'","",link),param$model,param$column,param$selection);
			}else browseURL(link);
		}
	}
	gSignalConnect(selection.main,"changed",change_text,list(model=model.main,buffer=buffer.main));
	gSignalConnect(textview.main,"event-after",link_clicked,list(model=model.main,column=column.main,selection=selection.main));
	## Initialize
	setListbox(topic,model.main,column.main,selection.main);
	## Show window
	window.main$add(hbox.main);
	hbox.main$packStart(sw1.main,FALSE,FALSE,2);
	hbox.main$packStart(sw2.main);
	sw1.main$add(listbox.main);
	sw2.main$add(textview.main);
	window.main$show();
}