*.Box,SetMouseCapture() captures all mouse-events, not only those within the Box

Author: FJuedesOrclCreated Dec 5, 2023Updated Aug 7, 2026

Hi Friends,

i am not sure if this is intentional, by mistake or technically unavoidable:

I have written a small application for which i want to improve the mouse-functionality, for example a double click on a table-row should open an edit-window.
I have created an example program (below) that configures a tview.Grid with a tview.TreeView to the left, a tview.Table to the right and a tview.TextView at the bottom as a status-line for debug-output.
I have attached a debug-printing MouseCapture function to the tview.Box element of the tview.TreeView only, but that function receives events from all over the screen.
My expectation was that, similar to an Input-Handler (*.SetInputCapture()) the MouseCapture function would only receive events within the boxes borders.

Am i doing something wrong? - Please have a look at the code below. Another question arose while writing the short experimental code: How can one map the mouse-event coordinates to a TUI-element? I am using flexible-grid dimensions, so that the dimensions of the elements are depending on the size of the terminal window.

Any hints and recommendations very welcomed!

Best regards from Charleston (WV), Frank/2

Here is the sample code:

package main

import (
  "fmt"
  "github.com/gdamore/tcell/v2"
  "github.com/rivo/tview"
)

func main() {
    // Configure a status-line for debug output
    Status := tview.NewTextView().SetText("Statusline")

    // Configure a Mouse-Capture function       
    MouseCapture := func(action tview.MouseAction, event *tcell.EventMouse) (tview.MouseAction, *tcell.EventMouse) {
      // Print the Mouse-Action as a bitmap
      Output := fmt.Sprintf("MouseAction: %%%016b; ",action)
      
      // Print the Mouse Buttons as bitmap
      buttons := event.Buttons()
      Output += fmt.Sprintf("MouseButtons: %%%016b; ",buttons)
      
      // Print the modifiers as bitmap
      modifiers := event.Modifiers()
      Output += fmt.Sprintf("Modifier Keys: %%%016b; ",modifiers)
      
      // Print the event-position
      PosX,PosY := event.Position()
      Output += fmt.Sprintf("PosX: %03d; PosY: %02d",PosX,PosY)
      
      // "print" output into status-line
      Status.SetText(Output)
      
      return action,event
    } // END MouseCapture

    // Configure a table with selectable rows
    Panel := tview.NewTable()
    Panel.SetBorders(true)
    Panel.SetBorderColor(tcell.NewRGBColor(127,127,127))
    Panel.SetSelectable(true,false)
    for row:=0;row<13;row++ {
      for col:=0;col<6;col++ {
        Panel.SetCell(row,col,tview.NewTableCell(fmt.Sprintf("row: %2d; col: %2d",row,col)).SetSelectable(true))
      } // END for col
    } // End for row
    
    // Configure a TreeView based menu
    RootNode := tview.NewTreeNode("ROOT").SetColor(tcell.NewRGBColor(255,15,15)).SetSelectable(true)
    for n:=0;n<10;n++ {
      node := tview.NewTreeNode(fmt.Sprintf("Node: %d",n)).SetColor(tcell.NewRGBColor(15,255,15)).SetSelectable(true)
      RootNode.AddChild(node)
    } // END for n
    
    Tree := tview.NewTreeView().SetRoot(RootNode).SetCurrentNode(RootNode).
                                SetGraphics(true).SetGraphicsColor(tcell.NewRGBColor(15,15,255))
    
    // !!!!!!!!!! We set the MouseCapture for the TreeView.Box only !!!!!!!!!!
    Tree.Box.SetBorder(true).SetMouseCapture(MouseCapture)                            
    
    // Configure a grid with the TreeView to the left, the Table to the right and the status-line at the bottom
    Grid := tview.NewGrid()
    Grid.SetColumns(-1,-3).SetRows(0,1).
         AddItem(Tree,0,0,1,1,0,0,true).
         AddItem(Panel,0,1,1,1,0,0,false).
         AddItem(Status,1,0,1,2,0,0,false)

    // Create and run the application
	app := tview.NewApplication().EnableMouse(true).SetMouseCapture(nil)
	if err := app.SetRoot(Grid, true).Run(); err != nil {
		panic(err)
	} // END if
} // END main

Source: rivo/tview

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