Make commandline show only after : is pressed

I have also attempted to make the commmand line hide when it is not in
focus, but had no luck.

src/commandline_content.ts

@@ -10,10 +10,16 @@
 */
 
 // inject the commandline iframe into a content page
-let clFrame = window.document.createElement("iframe")
-clFrame.setAttribute("src", browser.extension.getURL("static/commandline.html"))
-clFrame.setAttribute("style", "position: fixed; top: 0; left: 0; z-index: 10000; width: 100%; height: 36px; border: 0; padding: 0; margin: 0;");
-window.document.body.appendChild(clFrame)
+export function showcommandline(){
+    let clFrame = window.document.createElement("iframe")
+    clFrame.setAttribute("src", browser.extension.getURL("static/commandline.html"))
+    clFrame.setAttribute("style", "position: fixed; top: 0; left: 0; z-index: 10000; width: 100%; height: 36px; border: 0; padding: 0; margin: 0;");
+    window.document.body.appendChild(clFrame)
 
-/** Focus the commandline input */
-export let focus = ():void => clFrame.focus()
+    /** Focus the commandline input: not required **/
+    // let focus = ():void => clFrame.focus()
+    // line below doesn't work
+    clFrame.addEventListener("blur",clFrame.remove)
+    // Why were we returning focus? It's a void, surely?
+    // return focus
+}

src/excmds_background.ts

@@ -1,4 +1,5 @@
 /** Conventional definition of modulo that never gives a -ve result. */
+
 Number.prototype.mod = function (n: number): number {
     return Math.abs(this % n)
 }
@@ -89,6 +90,12 @@ export async function reload(n = 1, hard = false){
     )
 }
 
+// Commandline function
+
+export function showcommandline(){
+    messageActiveTab("showcommandline")
+}
+
 // TODO: address should default to some page to which we have access
 //          and focus the location bar
 export async function tabopen(address?: string){

src/excmds_content.ts

@@ -24,7 +24,7 @@ const commands = new Map<string, ContentCommand>([
         window.history.go(n)
     },
     function focuscmdline() {
-        CommandLineContent.focus()
+        CommandLineContent.showcommandline()
     }
 ].map((command):any => [command.name, command]))