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Move DisplayInternalUI from Core to BalExtension

User stories

  • As a Setup developer I can have more control over when my bundle shows the MSI UI such that I can keep using my existing MSI UI.


I looked through the wix-users list and users are asking for everything between DisplayInternalUI being configurable at runtime and wanting the full MSI UI for every operation (install/modify/repair/uninstall). There are 3 different approaches we can take in v4 for Burn.

  1. Remove DisplayInternalUI entirely. This enforces the design decision for Burn that there should be one unified UI for the bundle (documented in and

  2. Continue with the v3 design of DisplayInternalUI - allow the MSI UI to be shown, but the Burn engine will ensure that the user/MSI can only do what was planned. The basic idea to implement this approach is to expose MsiEngineCalculateInstallUiLevel as a BA message, but disallow certain UI levels when not doing an install. This satisfies some user requests but many want full MSI UI during maintenance operations, e.g. feature selection during Modify.

  3. Allow the BA full control of the UI level of the MSI, even if that means the user/MSI ends up doing something other than what was planned. The basic idea to implement this approach is to expose MsiEngineCalculateInstallUiLevel as a BA message, and allow disabling the Burn external UI handler to support EmbeddedUI. This should satisfy all user requests, or at least enable them to build a BA that can do what they want.

If we take #3 for Burn, then there are 3 similar approaches we can take for wixstdba.

  1. Remove support for displaying MSI UI.

  2. Continue with the v3 design of DisplayInternalUI. The basic idea behind this approach is to use the same logic that v3 Burn used to restrict uiLevel, so MSI UI is can only be shown during install. The external UI handler is always used.

  3. Allow the Setup developer to show MSI UI during non-install operations.

Proposal - Burn

Take approach #3. Add new event for OnPlanMsiPackage:

BURN_MSI_PROPERTY_NONE, // no property added

DWORD cbSize;
LPCWSTR wzPackageId;
BOOL fExecute; // false means rollback.

DWORD cbSize;
BOOL fCancel;
BURN_MSI_PROPERTY actionMsiProperty;
BOOL fDisableExternalUiHandler;

Burn will:

  • Call OnPlanMsiPackage for each MSI or MSP package authored in the chain, somewhere between OnPlanPackageBegin and OnPlanPackageComplete.
  • Default actionMsiProperty based on the planned action.
  • Always default fDisableExternalUiHandler to false.
  • Provide uiLevel and fDisableExternalUiHandler in BA_ONEXECUTEPACKAGEBEGIN_ARGS so the BA doesn't have to keep track of what it chose during plan.

Proposal - wixstdba

Take approach #3. Move the DisplayInternalUI attribute into the BalExtension. Modify the attribute to take a condition so that it can be configured at runtime, and rename it to DisplayInternalUICondition. If not specified, then internal UI will never be shown. The same condition is used for all operations. wixstdba will not change the value of actionMsiProperty. wixstdba will not support EmbeddedUI so it will not change the value of fDisableExternalUiHandler. This is because if the Setup developer has the resources to implement embedded UI, then they should spend those resources creating a custom theme for wixstdba or create a custom BA.

Proposal - UI.wixext

Teach all of the built-in UIs in UI.wixext about the new BURNMSIINSTALL, BURNMSIMODIFY, BURNMSIREPAIR, and BURNMSIUNINSTALL properties so that users are required to choose the same action they chose in the BA UI.


  • There are plans for adding a new built-in BA that will support EmbeddedUI.
  • Making Burn default uiLevel to INSTALLUILEVEL_NONE | INSTALLUILEVEL_SOURCERESONLY may change in the future since INSTALLUILEVEL_SOURCERESONLY might cause dialogs to be shown even if the bundle is supposed to be quiet.

See Also