A cleaner command-line

The minibuffer can be opened with ":". Some commands take arguments, and
if it's possible to present a selection of arguments that match a
prefix, the minibuffer displays them, vertically, above the partially
typed command. Prior to this commit, if the number of selections was
large, the list would exceed the space in the viewport and be cut off
uncleanly at the top of the terminal. This also had the unwanted
side-effect of having the minibuffer's list widget compute *all*
selections only to throw away (by trimming the rendered canvas of) the
selections that didn't fit on the screen. This change tracks the number
of currently available selections and stores that value in the widget
itself. At the same time, it adjusts the height argument, in units, of
the overlay used to contain the widget structure of the minibuffer,
including the list. When the minibuffer is rendered, it's in a box
context (columns and rows both specified). The list of selections will
ultimately be rendered in a box context, but with a small gowid change
too, the list's vertical space will be determined by the minimum of (a)
the computed number of selections and (b) the rows left in the
viewport. So all selections will be shows if they fit, and if there are
too many, the list itself will handle the cutoff. This means the cmdline
frame will render correctly too.

go.mod

@@ -9,7 +9,7 @@ require (
 	github.com/blang/semver v3.5.1+incompatible
 	github.com/fsnotify/fsnotify v1.4.9 // indirect
 	github.com/gcla/deep v1.0.2
-	github.com/gcla/gowid v1.2.1-0.20210817042717-048ae42d28f3
+	github.com/gcla/gowid v1.2.1-0.20210820032031-cfd3f37ca741
 	github.com/gcla/tail v1.0.1-0.20190505190527-650e90873359
 	github.com/gdamore/tcell v1.3.1-0.20200115030318-bff4943f9a29
 	github.com/go-test/deep v1.0.2 // indirect

go.sum

@@ -57,12 +57,8 @@ github.com/fsnotify/fsnotify v1.4.9 h1:hsms1Qyu0jgnwNXIxa+/V/PDsU6CfLf6CNO8H7IWo
 github.com/fsnotify/fsnotify v1.4.9/go.mod h1:znqG4EE+3YCdAaPaxE2ZRY/06pZUdp0tY4IgpuI1SZQ=
 github.com/gcla/deep v1.0.2 h1:qBOx6eepcOSRYnHJ+f2ih4hP4Vca1YnLtXxp73n5KWI=
 github.com/gcla/deep v1.0.2/go.mod h1:evE9pbpSGhItmFoBIk8hPOIC/keKTGYhFl6Le1Av+GE=
-github.com/gcla/gowid v1.2.1-0.20210730201604-e21cc1dff36b h1:mIGVx3Kq19ln5E25pwQtxCNmKi6rbrUhOgAtA1Vx+BE=
-github.com/gcla/gowid v1.2.1-0.20210730201604-e21cc1dff36b/go.mod h1:jQwZ6fAAnaylA+MkfgXLzjG0mTMStYixffw2jY0qG4k=
-github.com/gcla/gowid v1.2.1-0.20210806031049-f60cd69d4bd7 h1:4v2rkKvFsirRgM3C2UMPoxWxwM7Q9hlL/P31oB0YfIQ=
-github.com/gcla/gowid v1.2.1-0.20210806031049-f60cd69d4bd7/go.mod h1:jQwZ6fAAnaylA+MkfgXLzjG0mTMStYixffw2jY0qG4k=
-github.com/gcla/gowid v1.2.1-0.20210817042717-048ae42d28f3 h1:dWk9qzXXFwkWVP3UM+kJQ52FztZqof5cWx3Af6DG4t8=
-github.com/gcla/gowid v1.2.1-0.20210817042717-048ae42d28f3/go.mod h1:jQwZ6fAAnaylA+MkfgXLzjG0mTMStYixffw2jY0qG4k=
+github.com/gcla/gowid v1.2.1-0.20210820032031-cfd3f37ca741 h1:eeOU9lh9s7imJI/DMUxEwJS6vma8dC+d9ZKcxn8Nos4=
+github.com/gcla/gowid v1.2.1-0.20210820032031-cfd3f37ca741/go.mod h1:jQwZ6fAAnaylA+MkfgXLzjG0mTMStYixffw2jY0qG4k=
 github.com/gcla/tail v1.0.1-0.20190505190527-650e90873359 h1:3xEhacR7pIJV8daurdBygptxhzTJeYFqJp1V6SDl+pE=
 github.com/gcla/tail v1.0.1-0.20190505190527-650e90873359/go.mod h1:Wn+pZpM98JHSOYkPDtmdvlqmc0OzQGHWOsHB2d28WtQ=
 github.com/gcla/tcell v1.1.2-0.20200927150251-decc2045f510 h1:TlEZ0DHOvn0P79nHtkfemw7XFn2h8Lacd6AZpXrPU/o=

ui/ui.go

@@ -1441,7 +1441,7 @@ func lastLineMode(app gowid.IApp) {
 	MiniBuffer.Register("unmap", unmapCommand{w: keyMapper})
 	MiniBuffer.Register("help", helpCommand{})
 
-	minibuffer.Open(MiniBuffer, mbView, ratio(1.0), fixed, app)
+	minibuffer.Open(MiniBuffer, mbView, ratio(1.0), app)
 }
 
 //======================================================================

widgets/minibuffer/minibuffer.go

@@ -38,6 +38,7 @@ type Widget struct {
 	selections *list.Widget
 	ed         *edit.Widget
 	pl         *pile.Widget
+	ov         *overlay.Widget
 	showAll    bool // true if the user hits tab with nothing in the minibuffer. I don't
 	// want to display all completions if the buffer is empty because it fills the screen
 	// and looks ugly. So this is a hack to allow the completions to be displayed
@@ -146,11 +147,11 @@ func New() *Widget {
 		[]gowid.IContainerWidget{
 			&gowid.ContainerWidget{
 				IWidget: top,
-				D:       gowid.RenderFlow{},
+				D:       gowid.RenderWithWeight{W: 1},
 			},
 			&gowid.ContainerWidget{
 				IWidget: bottom,
-				D:       gowid.RenderFlow{},
+				D:       gowid.RenderWithUnits{U: 1},
 			},
 		},
 		pile.Options{
@@ -175,6 +176,7 @@ func New() *Widget {
 				BackgroundStyle: gowid.MakePaletteRef("cmdline"),
 				ButtonStyle:     gowid.MakePaletteRef("cmdline-button"),
 				BorderStyle:     gowid.MakePaletteRef("cmdline-border"),
+				Modal:           true,
 			},
 		),
 		compl:   top,
@@ -433,10 +435,13 @@ func (w *Widget) updateCompletions(app gowid.IApp) {
 
 	}
 
+	w.ov.SetHeight(gowid.RenderWithUnits{U: 3 + len(complWidgets)}, app)
+
 	walker := list.NewSimpleListWalker(complWidgets)
 	if len(complWidgets) > 0 {
 		walker.SetFocus(walker.Last(), app)
 		selections := list.New(walker)
+		selections.GoToBottom(app)
 		sl2 := keepselected.New(selections)
 		w.compl.SetSubWidget(sl2, app)
 		w.selections = selections
@@ -447,9 +452,11 @@ func (w *Widget) updateCompletions(app gowid.IApp) {
 	}
 }
 
-func Open(w dialog.IOpenExt, container gowid.ISettableComposite, width gowid.IWidgetDimension, height gowid.IWidgetDimension, app gowid.IApp) {
-	ov := overlay.New(w, container.SubWidget(),
-		gowid.VAlignBottom{}, height, // Intended to mean use as much vertical space as you need
+// w is minibuffer
+// container is main view
+func Open(w *Widget, container gowid.ISettableComposite, width gowid.IWidgetDimension, app gowid.IApp) {
+	w.ov = overlay.New(w, container.SubWidget(),
+		gowid.VAlignBottom{}, gowid.RenderWithUnits{U: 3}, // Intended to mean use as much vertical space as you need
 		gowid.HAlignLeft{Margin: 5, MarginRight: 5}, width)
 
 	if _, ok := width.(gowid.IRenderFixed); ok {
@@ -459,7 +466,7 @@ func Open(w dialog.IOpenExt, container gowid.ISettableComposite, width gowid.IWi
 	}
 	w.SetSavedSubWidget(container.SubWidget(), app)
 	w.SetSavedContainer(container, app)
-	container.SetSubWidget(ov, app)
+	container.SetSubWidget(w.ov, app)
 	w.SetOpen(true, app)
 }