property has the same value after setting it

问题:

Q:

I have a panel the visibility = false in the .aspx file ,at some point in my code i set the visibility = true.but the problem is: when i trace the code i find the visible property still equal false ,although i set it to true . My panel name is :pnl_DetailsGeneral

 protected void RadioButtonList1_SelectedIndexChanged(object sender, EventArgs e)
        {
            if (RadioButtonList1.SelectedValue == "2")
            {
                drp_Week.Enabled = false;
                gv_Details.Visible = false;
                panel_rmv.Visible = false;
                pnl_DetailsGeneral.Visible = true;//Here when i put a break point and after setting visible to true i find `pnl_DetailsGeneral.Visible = false`
                gv_DetailsGeneral.Visible = true;
                BindGridGeneral();

            }
            else if (RadioButtonList1.SelectedValue == "1")
            {
                drp_Week.Enabled = true;
                gv_Details.Visible = true;
                gv_DetailsGeneral.Visible = false;
                pnl_DetailsGeneral.Visible = false;
                if (drp_Week.SelectedValue != "-1")
                {

                    BindGrid();
                }
            }
        }

what may cause this problem?

回答1:

The Visible property has a special property: when you read the value it not only reports on the control itself but also on it's parent. The value you get is the "real" visibility.

So apparently the parent of your control is still invisible!

When you set the parent to Visible, your control will become visible also.

回答2:

I believe the Control.Visible property returns false if any parent has Visible = false.

回答3:

A possible explanation is implicit visibility through the control hierarchy.

For instance, if you have a placeholder than contains other controls, and the placeholder has visible set to false, all of it's child controls will also have Visible set the false, even if you set the property explicitly yourself.