fixing #959 textview mouse out of bounds fix

[digitallyserviced]

959 bails if user clicks on border of textview when regions enabled

• added *Box.InInnerRect(x,y int) helper to check if some coord is inside the inner rect (inside border/padding)
• added check using the helper within *TextView mouse handler to ensure that if regions are enabled, and will be checked, that the event occurred WITHIN the inner rect since borders/padding are excluded

package main

import (
        "fmt"
        "log"

        "github.com/rivo/tview"
)

func main() {
        tabs := tview.NewTextView().SetRegions(true)
        tabs.SetBorder(true)
                tabs.SetDynamicColors(true)

        myApp := tview.NewApplication()
        myApp.EnableMouse(true)
                // tabs.SetToggleHighlights(true)

        myFlex := tview.NewFlex().SetDirection(tview.FlexRow).
                AddItem(
                        tview.NewFlex().
                                AddItem(tabs, 30, 0, false),
                        5, 0, false,
                )

        fmt.Fprintf(tabs, `
["%s"][white]%s[""]
[red] vv %s vv
["%s"][green]%s[""]
`, "0", "Anything", "Long Text","2","Anythong")

        if err := myApp.SetRoot(myFlex, true).Run(); err != nil {
                log.Fatal(err)
        }
}