When maximizing in the UI, stay on the current view with focus

e.g. if the user is browsing the packet structure and hits '\', the
packet structure view should be maximized.

ui/ui.go

@@ -1606,10 +1606,54 @@ func mainKeyPress(evk *tcell.EventKey, app gowid.IApp) bool {
 				}
 			}
 		} else {
-			mainViewNoKeys.SetSubWidget(viewOnlyPacketList, app)
-			if deep.Equal(fp, maxViewPath) == nil {
-				gowid.SetFocusPath(viewOnlyPacketList, maxViewPath, app)
+			gotov := 0
+			if mainViewNoKeys.SubWidget() == mainview {
+				v1p := gowid.FocusPath(mainview)
+				if deep.Equal(v1p, mainviewPaths[0]) == nil {
+					gotov = 0
+				} else if deep.Equal(v1p, mainviewPaths[1]) == nil {
+					gotov = 1
+				} else {
+					gotov = 2
+				}
+			} else if mainViewNoKeys.SubWidget() == altview1 {
+				v2p := gowid.FocusPath(altview1)
+				if deep.Equal(v2p, altview1Paths[0]) == nil {
+					gotov = 0
+				} else if deep.Equal(v2p, altview1Paths[1]) == nil {
+					gotov = 1
+				} else {
+					gotov = 2
+				}
+			} else if mainViewNoKeys.SubWidget() == altview2 {
+				v3p := gowid.FocusPath(altview2)
+				if deep.Equal(v3p, altview2Paths[0]) == nil {
+					gotov = 0
+				} else if deep.Equal(v3p, altview2Paths[1]) == nil {
+					gotov = 1
+				} else {
+					gotov = 2
+				}
 			}
+
+			switch gotov {
+			case 0:
+				mainViewNoKeys.SetSubWidget(viewOnlyPacketList, app)
+				if deep.Equal(fp, maxViewPath) == nil {
+					gowid.SetFocusPath(viewOnlyPacketList, maxViewPath, app)
+				}
+			case 1:
+				mainViewNoKeys.SetSubWidget(viewOnlyPacketStructure, app)
+				if deep.Equal(fp, maxViewPath) == nil {
+					gowid.SetFocusPath(viewOnlyPacketStructure, maxViewPath, app)
+				}
+			case 2:
+				mainViewNoKeys.SetSubWidget(viewOnlyPacketHex, app)
+				if deep.Equal(fp, maxViewPath) == nil {
+					gowid.SetFocusPath(viewOnlyPacketHex, maxViewPath, app)
+				}
+			}
+
 		}
 	} else if isrune && evk.Rune() == '/' {
 		setFocusOnDisplayFilter(app)