Keep long content reachable
Put overflow inside a dedicated scrollable parent.
Scrolling solves reachability; it does not fix an incoherent layout. Set the content extent and parent relationship deliberately. A command inside the scrollable region must remain attached to that region when you scroll, while outside status controls stay fixed.
Step 1Prepare a safe practice project#
Extract the archive into a new writable folder, separate from your own application. Open ScrollContainer.mcproj in McBasic™. Keep every declared source, layout, resource and migration file together.
To reconstruct it yourself, create a DesktopApp project and add the files declared below. In the complete project, follow these steps as a guided rebuild: replace each named source file once and Check after all its procedures are present.
Exact project configuration
{
"schemaVersion": 1,
"projectId": "42bb890f-1fd0-42dd-bf32-a5fd4a3c2146",
"name": "ScrollContainerSample",
"kind": "DesktopApp",
"language": {
"dialect": "McBasic1",
"requireExplicit": true,
"compare": "Binary",
"defaultArrayBase": 0
},
"application": {
"bundleIdentifier": "com.mcbasic.samples.scrollcontainer",
"version": "0.1.0",
"buildNumber": "1",
"startupFormId": "form-main",
"shutdownMode": "OnStartupFormClosed"
},
"forms": [
{
"id": "form-main",
"typeName": "frmMain",
"layout": "Forms/frmMain.form.json",
"code": "Forms/frmMain.bas"
}
],
"modules": [],
"classes": [],
"tests": [],
"references": [],
"resources": [],
"targets": [
"osx-arm64"
],
"capabilities": []
}Step 2Build the Form and set its properties#
frmMain
Select the Form first and set its properties. Add containers before their children. These are initial Designer values, not statements to paste into a procedure.
| Form property | Value |
|---|---|
Caption | "ScrollContainer — McBasic" |
Width | 620 |
Height | 420 |
MinWidth | 500 |
MinHeight | 320 |
| Type | Name | Parent |
|---|---|---|
| ScrollContainer | scrMain | Form |
| CommandButton | cmdInside | scrMain |
| Label | lblInside | scrMain |
| StatusBar | staMain | Form |
| CommandButton | cmdClose | Form |
scrMain · exact Inspector values
| Property | Value |
|---|---|
Left | 48 |
Top | 40 |
Width | 524 |
Height | 270 |
HorizontalScrollBar | "Auto" |
VerticalScrollBar | "Auto" |
TabIndex | 0 |
| Anchor edges | Left, Right, Top, Bottom |
cmdInside · exact Inspector values
| Property | Value |
|---|---|
Left | 24 |
Top | 24 |
Width | 220 |
Height | 36 |
Caption | "Nested action" |
TabIndex | 0 |
| Anchor edges | Left, Top |
lblInside · exact Inspector values
| Property | Value |
|---|---|
Left | 24 |
Top | 340 |
Width | 720 |
Height | 34 |
Caption | "This authored child extends beyond the viewport and can be reached with the scroll bars." |
TabIndex | 1 |
| Anchor edges | Left, Top |
staMain · exact Inspector values
| Property | Value |
|---|---|
Left | 48 |
Top | 350 |
Width | 380 |
Height | 26 |
Text | "Ready" |
TabIndex | 1 |
| Anchor edges | Left, Bottom |
cmdClose · exact Inspector values
| Property | Value |
|---|---|
Left | 444 |
Top | 346 |
Width | 128 |
Height | 36 |
Caption | "Close" |
TabIndex | 2 |
| Anchor edges | Right, Bottom |
Step 3Connect the events explicitly#
frmMain
| Object | Event | Procedure | Parameters |
|---|---|---|---|
cmdInside | Click | cmdInside_Click | Click() |
cmdClose | Click | cmdClose_Click | Click() |
| Form | Load | Form_Load | () |
Step 4Enter the complete behavior#
Open the named source file. Enter declarations first, then every procedure. Expand a procedure for its full body, or copy the complete file. Helpers are required: do not stop after entering the first Click handler.
Forms/frmMain.bas
Enter these declarations at file scope, before the procedures.
Option ExplicitPrivate Sub Form_Load()
Initialize state before enabling dependent actions. Keep the shared declarations and startup dependencies with this procedure.
Private Sub Form_Load()
staMain.Text = "Horizontal: " & scrMain.HorizontalScrollBar & ", Vertical: " & scrMain.VerticalScrollBar
End SubPrivate Sub cmdInside_Click()
Enter the complete action, including its input checks and calls to helper procedures.
Private Sub cmdInside_Click()
staMain.Text = "Nested button clicked inside the scroll container."
End SubPrivate Sub cmdClose_Click()
Enter the complete action, including its input checks and calls to helper procedures.
Private Sub cmdClose_Click()
Unload Me
End SubCopy the complete Forms/frmMain.bas file
Replace the file once; do not append duplicate procedures.
Option Explicit
Private Sub Form_Load()
staMain.Text = "Horizontal: " & scrMain.HorizontalScrollBar & ", Vertical: " & scrMain.VerticalScrollBar
End Sub
Private Sub cmdInside_Click()
staMain.Text = "Nested button clicked inside the scroll container."
End Sub
Private Sub cmdClose_Click()
Unload Me
End SubStep 5Keep resources and storage reproducible#
No external resource or migration files are declared. Any inline migration, seed data or local JSON is present in the code above. Runtime application data and private preferences are not included in the archive.
Step 6Check, run and test the result#
Save all files and run Check. Resolve diagnostics before Run. Developer CLI users can work from the extracted folder:
mcbasic check ScrollContainer.mcproj
mcbasic run ScrollContainer.mcprojAcceptance checklist
- Scroll until the inner command is visible.
- Activate it and inspect the status.
- Resize the Form and confirm content remains reachable.
Step 7Make one change and repeat the tests#
Add another field below the original content and make sure it can be reached by keyboard and scrolling.
Save a working Git checkpoint first. Change one behavior, Check again and repeat the acceptance checklist. Compare with the downloaded solution if a regression appears.
20f4bfed6b · Build manifest