Renormalize the redraw function

Have all instances take a function
Update the remaining modules to take this into account
Numerous smaller refactors to make some widgets work more or less the same

modules/transmission/display.go

@@ -10,7 +10,14 @@ import (
 )
 
 func (widget *Widget) content() (string, string, bool) {
+	title := widget.CommonSettings().Title
+	if widget.err != nil {
+		return title, widget.err.Error(), true
+	}
 	data := widget.torrents
+	if data == nil || len(data) == 0 {
+		return title, "No data", false
+	}
 	str := ""
 
 	for idx, torrent := range data {
@@ -28,11 +35,11 @@ func (widget *Widget) content() (string, string, bool) {
 		str += utils.HighlightableHelper(widget.View, row, idx, len(torrName))
 	}
 
-	return widget.CommonSettings().Title, str, false
+	return title, str, false
 }
 
 func (widget *Widget) display() {
-	widget.ScrollableWidget.RedrawFunc(widget.content)
+	widget.ScrollableWidget.Redraw(widget.content)
 }
 
 func (widget *Widget) prettyTorrentName(name string) string {

modules/transmission/widget.go

@@ -16,6 +16,7 @@ type Widget struct {
 	client   *transmissionrpc.Client
 	settings *Settings
 	torrents []*transmissionrpc.Torrent
+	err      error
 }
 
 // NewWidget creates a new instance of a widget
@@ -63,14 +64,15 @@ func (widget *Widget) Fetch() ([]*transmissionrpc.Torrent, error) {
 func (widget *Widget) Refresh() {
 	torrents, err := widget.Fetch()
 	if err != nil {
+		widget.err = err
+		widget.torrents = nil
 		widget.SetItemCount(0)
-		widget.ScrollableWidget.Redraw(widget.CommonSettings().Title, err.Error(), false)
-		return
+	} else {
+		widget.err = nil
+		widget.torrents = torrents
+		widget.SetItemCount(len(torrents))
 	}
 
-	widget.torrents = torrents
-	widget.SetItemCount(len(torrents))
-
 	widget.display()
 }