gui: no screen stands in a theme override any more - the window's fonts are parsed twice rather than once per line

CHANGELOG.md

@@ -475,6 +475,16 @@ because it turns other people's test suites red.
 
 ### Fixed
 
+- **The window uses far less memory, and rebuilding a screen no longer adds
+  to it.** Every
+  quiet line on a screen - a subtitle, a caption, the count of bytes beside a
+  size, the line a folded section keeps, the message under a field - parsed
+  its own copy of the fonts, and parsed another each time the screen was
+  rebuilt and the line said something new. After visiting the four tabs the
+  window held about 290 MB and it now holds about 120 MB, and rebuilding a
+  screen no longer adds to it. Nothing on the screen looks different. The open
+  list of formats still does this when you type into its filter, and is next.
+
 - **The `Several batches` screen no longer slows down the longer it is
   used.** Every batch added, removed or copied, every format chosen and every
   press of `Start from a preset` made each box on the screen report a change

internal/guard/leftedge_test.go

@@ -138,7 +138,9 @@ func TestTheActionBarSpeaksOnTheSameEdgeAsTheForm(t *testing.T) {
 	if status == nil {
 		t.Fatal("the bar is not naming the destination at rest, so this guard read the wrong tree")
 	}
-	at, found := absoluteOf(generate, status)
+	// Measured where its words are, which labelBox knows for a line drawn
+	// ink tight - the label itself stands one padding to the left of them.
+	at, found := labelBox(generate, status.Text)
 	if !found {
 		t.Fatal("the status line is not on the screen it was found in")
 	}

internal/guard/spacingscale_test.go

@@ -239,17 +239,34 @@ func gapBelowField(t *testing.T, screen fyne.CanvasObject, above, below string)
 //
 // Found by the text on the label rather than by a position handed in, because
 // a guard given coordinates would be a copy of the layout it is checking.
+//
+// A sentence drawn ink tight (parts.inkTight) is measured by the room it was
+// given, not by the label. Since 2026-09-23 the layout places the label one
+// inner padding up and left and one larger on every side, so its padding falls
+// outside the room and its words land on the room's edge - the label's own
+// box is where its padding is, and the room is where the ink is, exactly
+// where the label stood when a theme override took the padding off instead.
 func labelBox(screen fyne.CanvasObject, words string) (band, bool) {
 	found := band{}
 	ok := false
+	tight := map[fyne.CanvasObject]band{}
 	atAbsolute(screen, func(o fyne.CanvasObject, at fyne.Position) {
 		if ok {
 			return
 		}
+		if room, is := o.(*fyne.Container); is && len(room.Objects) == 1 {
+			if p := room.Objects[0].Position(); p.X < 0 && p.X == p.Y {
+				tight[room.Objects[0]] = band{X: at.X, Y: at.Y, Width: room.Size().Width, Height: room.Size().Height}
+			}
+		}
 		shown, is := wordsOf(o)
 		if !is || shown != words {
 			return
 		}
+		if room, drawnTight := tight[o]; drawnTight {
+			found, ok = room, true
+			return
+		}
 		found, ok = band{X: at.X, Y: at.Y, Width: o.Size().Width, Height: o.Size().Height}, true
 	})
 	return found, ok