dirtree: modify drawing of the dirtree

Update the dirtree drawing structure to be a bit more compact. The
dirtree is drawn with one column left for a flag, which indicates if a
parent is collapsed or expanded. Only draw the "flag" when the parent is
collapsed. Change the flag to a '+' character to match common UI
patterns of expanding lists having a '+' box.

Don't draw the '>' character in the dirtree. This character is nice in
the threaded message view, but clutters up the dirtree. I know this is a
matter of preference, but this approach is similar to most other UI tree
view and gives the dirtree an extra column of space.

The original dirtree looks like this:
	┌Inbox
	├─>Sub
	└─>Sub

And collapsed:
	-Inbox

This patch changes it to:
	Inbox
	├─Sub
	└─Sub

And collapsed:
	+Inbox

Signed-off-by: Tim Culverhouse <tim@timculverhouse.com>
Acked-by: Moritz Poldrack <moritz@poldrack.dev>

1 files changed, 8 insertions, 9 deletions

diff --git a/widgets/dirtree.go b/widgets/dirtree.go
index b0943ae4..41477c5f 100644
--- a/widgets/dirtree.go
+++ b/widgets/dirtree.go
@@ -275,7 +275,7 @@ func (dt *DirectoryTree) countVisible(list []*types.Thread) (n int) {
 
 func (dt *DirectoryTree) displayText(node *types.Thread) string {
 	elems := strings.Split(dt.treeDirs[getAnyUid(node)], dt.pathSeparator)
-	return fmt.Sprintf("%s%s%s", threadPrefix(node, false), getFlag(node), elems[countLevels(node)])
+	return fmt.Sprintf("%s%s%s", threadPrefix(node, false, false), getFlag(node), elems[countLevels(node)])
 }
 
 func (dt *DirectoryTree) getDirectory(node *types.Thread) string {
@@ -471,13 +471,12 @@ func countLevels(node *types.Thread) (level int) {
 	return
 }
 
-func getFlag(node *types.Thread) (flag string) {
-	if node != nil && node.FirstChild != nil {
-		if node.Hidden {
-			flag = "─"
-		} else {
-			flag = "┌"
-		}
+func getFlag(node *types.Thread) string {
+	if node == nil && node.FirstChild == nil {
+		return ""
 	}
-	return
+	if node.Hidden {
+		return "+"
+	}
+	return ""
 }